Restructure project

19 files changed, 1417 insertions, 0 deletions

diff --git a/include/gfx/asset.h b/include/gfx/asset.h
new file mode 100644
index 0000000..caf40c1
--- /dev/null
+++ b/include/gfx/asset.h
@@ -0,0 +1,99 @@
+/* Asset Management */
+#pragma once
+
+#include <gfx/core.h>
+
+#include <stddef.h>
+
+typedef struct Gfx           Gfx;
+typedef struct Model         Model;
+typedef struct ShaderProgram ShaderProgram;
+typedef struct Texture       Texture;
+
+/// Describes where the asset comes from.
+typedef enum AssetOrigin {
+  AssetFromMemory,
+  AssetFromFile,
+} AssetOrigin;
+
+/// Describes a texture's colour space.
+typedef enum TextureColourSpace {
+  sRGB, // The most likely default.
+  LinearColourSpace,
+} TextureColourSpace;
+
+/// Describes a command to load a texture.
+typedef struct LoadTextureCmd {
+  AssetOrigin origin;
+  enum { LoadTexture, LoadCubemap } type;
+  TextureColourSpace colour_space;
+  TextureFiltering   filtering;
+  TextureWrapping    wrap;
+  bool               mipmaps;
+  union {
+    // A single texture.
+    struct {
+      union {
+        struct {
+          mstring filepath;
+        };
+        struct {
+          const void* data;
+          size_t      size_bytes;
+        };
+      };
+    } texture;
+    // Cubemap texture.
+    struct {
+      union {
+        struct {
+          mstring filepath_pos_x;
+          mstring filepath_neg_x;
+          mstring filepath_pos_y;
+          mstring filepath_neg_y;
+          mstring filepath_pos_z;
+          mstring filepath_neg_z;
+        } filepaths;
+        struct {
+          const void* data_pos_x;
+          const void* data_neg_x;
+          const void* data_pos_y;
+          const void* data_neg_y;
+          const void* data_pos_z;
+          const void* data_neg_z;
+        } buffers;
+      };
+    } cubemap;
+  } data;
+} LoadTextureCmd;
+
+/// Describes a command to load a model.
+///
+/// |shader| is an optional shader program assigned to the loaded model objects.
+/// If no shader is given, a Cook-Torrance shader based on the object's
+/// characteristics (presence of normals, tangents, etc) is assigned.
+typedef struct LoadModelCmd {
+  AssetOrigin origin;
+  union {
+    struct {
+      mstring filepath;
+    };
+    struct {
+      const void* data;
+      size_t      size_bytes;
+    };
+  };
+  ShaderProgram* shader;
+} LoadModelCmd;
+
+/// Load a model.
+///
+/// For animated models, this function returns a (shallow) clone of the model
+/// that is safe to mutate. For static models, this returns the original model
+/// in the cache.
+///
+/// Currently only supports the GLTF format.
+Model* gfx_load_model(Gfx*, const LoadModelCmd*);
+
+/// Load a texture.
+const Texture* gfx_load_texture(Gfx*, const LoadTextureCmd*);
diff --git a/include/gfx/core.h b/include/gfx/core.h
new file mode 100644
index 0000000..44509c9
--- /dev/null
+++ b/include/gfx/core.h
@@ -0,0 +1,501 @@
+/// Render Backend.
+///
+/// The Render Backend creates and owns graphics objects and performs low-level
+/// rendering operations.
+#pragma once
+
+#include "sizes.h"
+
+#include <math/aabb3.h>
+#include <math/fwd.h>
+#include <math/mat4.h>
+#include <math/vec4.h>
+
+#include <cstring.h>
+
+#include <stddef.h>
+#include <stdint.h>
+
+// Implementation objects.
+typedef struct Buffer        Buffer;
+typedef struct FrameBuffer   FrameBuffer;
+typedef struct Geometry      Geometry;
+typedef struct GfxCore       GfxCore;
+typedef struct RenderBuffer  RenderBuffer;
+typedef struct Shader        Shader;
+typedef struct ShaderProgram ShaderProgram;
+typedef struct Texture       Texture;
+
+/// Data type for vertex indices.
+/// Might need U32 for bigger models.
+typedef uint8_t  VertexIndex8;
+typedef uint16_t VertexIndex16;
+typedef uint16_t VertexCount;
+
+/// Geometry drawing modes.
+typedef enum PrimitiveType {
+  Triangles,
+  TriangleFan,
+  TriangleStrip
+} PrimitiveType;
+
+/// Buffer usage.
+typedef enum BufferUsage { BufferStatic, BufferDynamic } BufferUsage;
+
+/// Buffer type.
+typedef enum BufferType {
+  BufferUntyped,
+  Buffer2d,
+  Buffer3d,
+  Buffer4d,
+  BufferFloat,
+  BufferU8,
+  BufferU16
+} BufferType;
+
+/// Buffer data descriptor.
+typedef struct BufferDataDesc {
+  union {
+    const void*     data;
+    const vec2*     vec2s;
+    const vec3*     vec3s;
+    const float*    floats;
+    const uint8_t*  u8s;
+    const uint16_t* u16s;
+  };
+  size_t count;
+} BufferDataDesc;
+
+/// Buffer descriptor.
+///
+/// 'count' is the number of elements in the array. For untyped buffers, this is
+/// the size in bytes of the 'data' array. For other types, it is the number of
+/// vec2s, vec3s, etc. in the corresponding array.
+///
+/// The data pointers can also be null. In such a case, a buffer of the given
+/// size is created with its contents uninitialized.
+///
+/// TODO: Think about typed buffers (Buffer, Buffer2d, Buffer3d, BufferU8, etc).
+/// Typed buffers don't work well with interleaved vertex attributes. Not sure
+/// this is really worth it.
+typedef struct BufferDesc {
+  BufferUsage    usage;
+  BufferType     type;
+  BufferDataDesc data;
+} BufferDesc;
+
+/// A buffer view for vertex data (attributes or indices).
+/// Either 'data' or 'buffer' must be set.
+#define MAKE_BUFFER_VIEW(NAME, TYPE) \
+  typedef struct NAME {              \
+    const TYPE* data;                \
+    Buffer*     buffer;              \
+    size_t      offset_bytes;        \
+    size_t      size_bytes;          \
+    size_t      stride_bytes;        \
+  } NAME;
+
+/// A buffer view for untyped data.
+MAKE_BUFFER_VIEW(BufferView, void)
+
+/// A buffer view for 2D vectors.
+MAKE_BUFFER_VIEW(BufferView2d, vec2)
+
+/// A buffer view for 3D vectors.
+MAKE_BUFFER_VIEW(BufferView3d, vec3)
+
+/// A buffer view for 4D vectors.
+MAKE_BUFFER_VIEW(BufferView4d, vec4)
+
+/// A buffer view for floats.
+MAKE_BUFFER_VIEW(BufferViewFloat, float)
+
+/// A buffer view for 8-bit unsigned integers.
+MAKE_BUFFER_VIEW(BufferViewU8, uint8_t)
+
+/// A buffer view for 16-bit unsigned integers.
+MAKE_BUFFER_VIEW(BufferViewU16, uint16_t)
+
+/// A buffer view for 8-bit vertex indices.
+MAKE_BUFFER_VIEW(BufferViewIdx8, uint16_t)
+
+/// A buffer view for 16-bit vertex indices.
+MAKE_BUFFER_VIEW(BufferViewIdx16, uint16_t)
+
+/// Describes a piece of geometry.
+///
+/// Buffer views may point to either already-existing GPU buffers or to data in
+/// host memory.
+///
+/// If the buffer views do not already point to GPU buffers, GPU buffers are
+/// created for the geometry. The 'buffer_usage' field specifies the usage for
+/// the created buffers. Use BufferStatic for static geometry and BufferDynamic
+/// for dynamic geometry.
+///
+/// Currently we support only up to 16-bit vertex indices. Might have to change
+/// this to support a larger variety of 3D models.
+typedef struct GeometryDesc {
+  BufferView2d positions2d;
+  BufferView3d positions3d;
+  BufferView3d normals;
+  BufferView4d tangents;
+  BufferView2d texcoords;
+  struct {
+    BufferViewU8  u8;
+    BufferViewU16 u16;
+  } joints; // uvec4.
+  struct {
+    BufferViewFloat floats;
+    BufferViewU8    u8;
+    BufferViewU16   u16;
+  } weights; // vec4 or uvec4.
+  BufferViewIdx8  indices8;
+  BufferViewIdx16 indices16;
+  VertexCount     num_verts;
+  size_t          num_indices;
+  PrimitiveType   type;
+  BufferUsage     buffer_usage;
+  aabb3           aabb;
+} GeometryDesc;
+
+/// Shader compiler define.
+typedef struct ShaderCompilerDefine {
+  sstring name;
+  sstring value;
+} ShaderCompilerDefine;
+
+/// Shader types.
+typedef enum { VertexShader, FragmentShader } ShaderType;
+
+/// Describes a shader.
+typedef struct ShaderDesc {
+  ShaderType           type;
+  const char*          code;
+  ShaderCompilerDefine defines[GFX_MAX_SHADER_COMPILER_DEFINES];
+  size_t               num_defines;
+} ShaderDesc;
+
+/// Describes a shader program.
+typedef struct ShaderProgramDesc {
+  const Shader* vertex_shader;
+  const Shader* fragment_shader;
+} ShaderProgramDesc;
+
+/// Shader uniform type.
+typedef enum {
+  UniformFloat,
+  UniformMat4,
+  UniformTexture,
+  UniformVec3,
+  UniformVec4,
+  UniformMat4Array
+} UniformType;
+
+/// Shader uniform.
+///
+/// For uniform arrays, the client must ensure that the array is still valid by
+/// the time the uniform data is passed to the GPU.
+typedef struct ShaderUniform {
+  sstring     name;
+  UniformType type;
+  union {
+    const Texture* texture;
+    mat4           mat4;
+    vec3           vec3;
+    vec4           vec4;
+    float          scalar;
+    struct {
+      size_t count;
+      union {
+        const mat4* values;
+      };
+    } array;
+  } value;
+} ShaderUniform;
+
+/// Texture dimension.
+typedef enum { Texture2D, TextureCubeMap } TextureDimension;
+
+/// Texture data format.
+typedef enum {
+  TextureDepth,
+  TextureRG16,
+  TextureRG16F,
+  TextureRGB8,
+  TextureR11G11B10F,
+  TextureRGBA8,
+  TextureSRGB8,
+  TextureSRGBA8
+} TextureFormat;
+
+/// Texture filtering.
+typedef enum { NearestFiltering, LinearFiltering } TextureFiltering;
+
+/// Texture wrap mode.
+typedef enum { Repeat, ClampToEdge } TextureWrapping;
+
+/// Cubemap faces.
+typedef enum {
+  CubemapFacePosX,
+  CubemapFaceNegX,
+  CubemapFacePosY,
+  CubemapFaceNegY,
+  CubemapFacePosZ,
+  CubemapFaceNegZ
+} CubemapFace;
+
+/// Texture data descriptor.
+typedef struct TextureDataDesc {
+  union {
+    const void* pixels;
+    struct {
+      const void* pixels_pos_x;
+      const void* pixels_neg_x;
+      const void* pixels_pos_y;
+      const void* pixels_neg_y;
+      const void* pixels_pos_z;
+      const void* pixels_neg_z;
+    } cubemap;
+  };
+} TextureDataDesc;
+
+/// Describes a texture.
+typedef struct TextureDesc {
+  int              width;
+  int              height;
+  int              depth; // Not used until 3D textures are exposed.
+  TextureDimension dimension;
+  TextureFormat    format;
+  TextureFiltering filtering;
+  TextureWrapping  wrap;
+  bool             mipmaps;
+  TextureDataDesc  data;
+} TextureDesc;
+
+/// Describes a renderbuffer.
+typedef struct RenderBufferDesc {
+  int           width;
+  int           height;
+  TextureFormat texture_format;
+} RenderBufferDesc;
+
+/// Framebuffer attachment type.
+typedef enum FrameBufferAttachmentType {
+  FrameBufferNoAttachment,
+  FrameBufferTexture,
+  FrameBufferCubemapTexture,
+  FrameBufferRenderBuffer
+} FrameBufferAttachmentType;
+
+/// Describes a framebuffer attachment.
+typedef struct FrameBufferAttachment {
+  FrameBufferAttachmentType type;
+  union {
+    struct {
+      Texture* texture;
+      int      mip_level;
+    } texture;
+    struct {
+      Texture*    texture;
+      int         mip_level;
+      CubemapFace face;
+    } cubemap;
+    RenderBuffer* renderbuffer;
+  };
+} FrameBufferAttachment;
+
+/// Describes a framebuffer.
+typedef struct FrameBufferDesc {
+  FrameBufferAttachment colour;
+  FrameBufferAttachment depth;
+} FrameBufferDesc;
+
+// -----------------------------------------------------------------------------
+// Render commands.
+// -----------------------------------------------------------------------------
+
+/// Start a new frame.
+void gfx_start_frame(GfxCore*);
+
+/// End a frame.
+void gfx_end_frame(GfxCore*);
+
+/// Set the render backend's viewport dimensions.
+void gfx_set_viewport(GfxCore*, int x, int y, int width, int height);
+
+/// Get the render backend's viewport dimensions.
+void gfx_get_viewport(GfxCore*, int* x, int* y, int* width, int* height);
+
+/// Clear the viewport.
+void gfx_clear(GfxCore*, vec4 colour);
+
+/// Set blending state.
+void gfx_set_blending(GfxCore*, bool enable);
+
+/// Set depth mask.
+void gfx_set_depth_mask(GfxCore*, bool enable);
+
+/// Set cull mode.
+void gfx_set_culling(GfxCore*, bool enable);
+
+/// Set polygon offset.
+void gfx_set_polygon_offset(GfxCore*, float scale, float bias);
+
+/// Reset the polygon offset.
+void gfx_reset_polygon_offset(GfxCore*);
+
+// -----------------------------------------------------------------------------
+// Buffers.
+// -----------------------------------------------------------------------------
+
+/// Create a buffer from raw data.
+Buffer* gfx_make_buffer(GfxCore*, const BufferDesc*);
+
+/// Destroy the buffer.
+void gfx_destroy_buffer(GfxCore*, Buffer**);
+
+/// Update the buffer's data.
+void gfx_update_buffer(Buffer*, const BufferDataDesc*);
+
+// -----------------------------------------------------------------------------
+// Geometry.
+// -----------------------------------------------------------------------------
+
+/// Create geometry.
+Geometry* gfx_make_geometry(GfxCore*, const GeometryDesc*);
+
+/// Destroy the geometry.
+void gfx_destroy_geometry(GfxCore*, Geometry**);
+
+/// Upload new vertex data for the geometry.
+///
+/// This is similar to gfx_make_geometry(), but the geometry need not be
+/// entirely specified.
+///
+/// Only the vertex attributes, vertex count, and index count set in the
+/// descriptor are updated. Index data, primitive type, and other properties of
+/// the geometry are not updated.
+///
+/// New data must be given as arrays in host memory. That is, the buffer views
+/// in the descriptor must point to CPU arrays, not GPU buffers.
+///
+/// Note that the descriptor cannot specify a larger vertex or index count than
+/// what the geometry was created with. If the geometry size or any other
+/// attribute not handled by this update function needs to be changed, then a
+/// new geometry must be created.
+void gfx_update_geometry(Geometry*, const GeometryDesc*);
+
+/// Render the geometry.
+void gfx_render_geometry(const Geometry*);
+
+/// Return the geometry's bounding box.
+aabb3 gfx_get_geometry_aabb(const Geometry*);
+
+// -----------------------------------------------------------------------------
+// Textures.
+// -----------------------------------------------------------------------------
+
+/// Create a texture.
+Texture* gfx_make_texture(GfxCore*, const TextureDesc*);
+
+/// Destroy the texture.
+void gfx_destroy_texture(GfxCore*, Texture**);
+
+/// Update the texture.
+void gfx_update_texture(Texture*, const TextureDataDesc*);
+
+// -----------------------------------------------------------------------------
+// Renderbuffers.
+// -----------------------------------------------------------------------------
+
+/// Create a renderbuffer.
+RenderBuffer* gfx_make_renderbuffer(GfxCore*, const RenderBufferDesc*);
+
+/// Destroy the renderbuffer.
+void gfx_destroy_renderbuffer(GfxCore*, RenderBuffer**);
+
+// -----------------------------------------------------------------------------
+// Framebuffers.
+// -----------------------------------------------------------------------------
+
+/// Create a framebuffer.
+FrameBuffer* gfx_make_framebuffer(GfxCore*, const FrameBufferDesc*);
+
+/// Destroy the framebuffer.
+void gfx_destroy_framebuffer(GfxCore*, FrameBuffer**);
+
+/// Attach a colour buffer to the framebuffer.
+bool gfx_framebuffer_attach_colour(FrameBuffer*, const FrameBufferAttachment*);
+
+/// Attach a depth buffer to the framebuffer.
+bool gfx_framebuffer_attach_depth(FrameBuffer*, const FrameBufferAttachment*);
+
+/// Activate the framebuffer.
+/// Subsequent draw calls write to this framebuffer.
+void gfx_activate_framebuffer(const FrameBuffer*);
+
+/// Deactivate the framebuffer.
+/// Subsequent draw calls write to the default framebuffer.
+void gfx_deactivate_framebuffer(const FrameBuffer*);
+
+/// Set the framebuffer's viewport.
+/// This function should be called every time the framebuffer is activated.
+void gfx_framebuffer_set_viewport(
+    FrameBuffer*, int x, int y, int width, int height);
+
+// -----------------------------------------------------------------------------
+// Shaders.
+// -----------------------------------------------------------------------------
+
+/// Create a shader.
+Shader* gfx_make_shader(GfxCore*, const ShaderDesc*);
+
+/// Destroy the shader.
+void gfx_destroy_shader(GfxCore*, Shader**);
+
+/// Create a shader program.
+ShaderProgram* gfx_make_shader_program(GfxCore*, const ShaderProgramDesc*);
+
+/// Destroy the shader program.
+void gfx_destroy_shader_program(GfxCore*, ShaderProgram**);
+
+/// Activate the shader program.
+void gfx_activate_shader_program(const ShaderProgram*);
+
+/// Deactivate the shader program.
+void gfx_deactivate_shader_program(const ShaderProgram*);
+
+/// Apply the shader program's uniform variables.
+///
+/// Calls to gfx_set_XYZ_uniform save the values of the uniform variables in the
+/// graphics library. By calling this function, those values are passed on to
+/// the graphics driver for rendering.
+///
+/// This function should be called after setting all of the uniform variables
+/// and prior to issuing a draw call.
+void gfx_apply_uniforms(const ShaderProgram*);
+
+/// Set the texture uniform.
+/// Has no effect if the shader does not contain the given uniform.
+void gfx_set_texture_uniform(ShaderProgram*, const char* name, const Texture*);
+
+/// Set the matrix uniform.
+/// Has no effect if the shader does not contain the given uniform.
+void gfx_set_mat4_uniform(ShaderProgram*, const char* name, const mat4*);
+
+/// Set the vec3 uniform.
+/// Has no effect if the shader does not contain the given uniform.
+void gfx_set_vec3_uniform(ShaderProgram*, const char* name, vec3);
+
+/// Set the vec4 uniform.
+/// Has no effect if the shader does not contain the given uniform.
+void gfx_set_vec4_uniform(ShaderProgram*, const char* name, vec4);
+
+/// Set the float uniform.
+/// Has no effect if the shader does not contain the given uniform.
+void gfx_set_float_uniform(ShaderProgram*, const char* name, float value);
+
+/// Set the matrix array uniform.
+/// Has no effect if the shader does not contain the given uniform.
+void gfx_set_mat4_array_uniform(
+    ShaderProgram*, const char* name, const mat4*, size_t count);
diff --git a/include/gfx/gfx.h b/include/gfx/gfx.h
new file mode 100644
index 0000000..7c670a5
--- /dev/null
+++ b/include/gfx/gfx.h
@@ -0,0 +1,31 @@
+#pragma once
+
+typedef struct AssetCache  AssetCache;
+typedef struct GfxCore     GfxCore;
+typedef struct ImmRenderer ImmRenderer;
+typedef struct Renderer    Renderer;
+
+typedef struct Gfx Gfx;
+
+/// Create a new graphics system,
+Gfx* gfx_init(void);
+
+/// Destroy the graphics system.
+void gfx_destroy(Gfx**);
+
+/// Get the render backend.
+GfxCore* gfx_get_core(Gfx*);
+
+/// Get the renderer.
+Renderer* gfx_get_renderer(Gfx*);
+
+/// Get the immediate mode renderer.
+ImmRenderer* gfx_get_imm_renderer(Gfx*);
+
+/// Get the asset cache.
+AssetCache* gfx_get_asset_cache(Gfx*);
+
+/// Remove unused resources from the scene (meshes, materials).
+/// TODO: need to think about the interface for scene_purge(). Maybe this
+/// should be gfx_purge() and take a list of Scenes?
+// void gfx_purge(Scene*);
diff --git a/include/gfx/renderer.h b/include/gfx/renderer.h
new file mode 100644
index 0000000..2a4ada1
--- /dev/null
+++ b/include/gfx/renderer.h
@@ -0,0 +1,104 @@
+#pragma once
+
+#include <math/aabb2.h>
+#include <math/aabb3.h>
+#include <math/camera.h>
+#include <math/defs.h>
+#include <math/mat4.h>
+#include <math/vec3.h>
+#include <math/vec4.h>
+
+typedef struct GfxCore     GfxCore;
+typedef struct Scene       Scene;
+typedef struct SceneCamera SceneCamera;
+
+typedef struct ImmRenderer ImmRenderer;
+typedef struct Renderer    Renderer;
+
+// -----------------------------------------------------------------------------
+// Main Renderer.
+// -----------------------------------------------------------------------------
+
+typedef enum RenderSceneMode {
+  RenderDefault,
+  RenderDebug,
+  RenderNormals,
+  RenderNormalMappedNormals,
+  RenderTangents
+} RenderSceneMode;
+
+typedef struct RenderSceneParams {
+  RenderSceneMode    mode;
+  const Scene*       scene;
+  const SceneCamera* camera;
+} RenderSceneParams;
+
+/// Render the scene.
+void gfx_render_scene(Renderer*, const RenderSceneParams*);
+
+/// Update the scene.
+void gfx_update(Scene*, const SceneCamera*, R t);
+
+// -----------------------------------------------------------------------------
+// Immediate Mode Renderer.
+// -----------------------------------------------------------------------------
+
+/// Prepare the graphics systems for immediate-mode rendering.
+///
+/// Call this before issuing any immediate-mode rendering draws.
+void gfx_imm_start(ImmRenderer*);
+
+/// End immediate mode rendering.
+///
+/// Call this after issuing immediate-mode rendering draws and before swapping
+/// buffers.
+void gfx_imm_end(ImmRenderer*);
+
+/// Draw a set of triangles.
+void gfx_imm_draw_triangles(ImmRenderer*, const vec3[], size_t num_triangles);
+
+/// Draw a triangle.
+void gfx_imm_draw_triangle(ImmRenderer*, const vec3[3]);
+
+/// Draw a bounding box.
+void gfx_imm_draw_aabb2(ImmRenderer*, aabb2);
+
+/// Draw a bounding box.
+void gfx_imm_draw_aabb3(ImmRenderer*, aabb3);
+
+/// Draw a box.
+///
+/// The vertices must be given in the following order:
+///
+///     7 ----- 6
+///    /       /|
+///   3 ----- 2 |
+///   |       | |
+///   | 4 ----- 5
+///   |/      |/
+///   0 ----- 1
+void gfx_imm_draw_box3(ImmRenderer* renderer, const vec3 vertices[8]);
+
+/// Set the camera.
+void gfx_imm_set_camera(ImmRenderer*, const Camera*);
+
+/// Load an identity model matrix. Clears the matrix stack.
+void gfx_imm_load_identity(ImmRenderer* renderer);
+
+/// Push the given matrix to the matrix stack.
+void gfx_imm_push_matrix(ImmRenderer* renderer, const mat4* matrix);
+
+/// Pop the top of the matrix stack.
+void gfx_imm_pop_matrix(ImmRenderer* renderer);
+
+/// Push a translation matrix to the matrix stack.
+void gfx_imm_translate(ImmRenderer* renderer, vec3 offset);
+
+/// Set the model matrix. Clears the matrix stack.
+void gfx_imm_set_model_matrix(ImmRenderer*, const mat4*);
+
+/// Set the view-projection matrix.
+void gfx_imm_set_view_projection_matrix(ImmRenderer*, const mat4*);
+
+/// Set the render colour.
+void gfx_imm_set_colour(ImmRenderer*, vec4 colour);
diff --git a/include/gfx/scene.h b/include/gfx/scene.h
new file mode 100644
index 0000000..abcaa70
--- /dev/null
+++ b/include/gfx/scene.h
@@ -0,0 +1,11 @@
+#pragma once
+
+#include <gfx/scene/animation.h>
+#include <gfx/scene/camera.h>
+#include <gfx/scene/light.h>
+#include <gfx/scene/material.h>
+#include <gfx/scene/mesh.h>
+#include <gfx/scene/model.h>
+#include <gfx/scene/node.h>
+#include <gfx/scene/object.h>
+#include <gfx/scene/scene.h>
diff --git a/include/gfx/scene/animation.h b/include/gfx/scene/animation.h
new file mode 100644
index 0000000..d95b895
--- /dev/null
+++ b/include/gfx/scene/animation.h
@@ -0,0 +1,142 @@
+#pragma once
+
+#include "node.h"
+#include "object.h"
+#include <gfx/sizes.h>
+
+#include <cstring.h>
+#include <math/aabb3.h>
+#include <math/defs.h>
+#include <math/mat4.h>
+#include <math/quat.h>
+#include <math/vec3.h>
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+typedef struct Buffer    Buffer;
+typedef struct SceneNode SceneNode;
+
+typedef struct Anima    Anima;
+typedef struct Joint    Joint;
+typedef struct Skeleton Skeleton;
+
+/// Index type used to store relative indices into arrays.
+typedef uint16_t joint_idx;
+
+/// Index value denoting no index.
+static const joint_idx INDEX_NONE = (joint_idx)-1;
+
+typedef struct Box {
+  vec3 vertices[8];
+} Box;
+
+/// Joint descriptor.
+typedef struct JointDesc {
+  joint_idx parent;      /// Parent Joint; index into Anima's joints.
+  mat4  inv_bind_matrix; /// Transforms the mesh into the joint's local space.
+  aabb3 box;             /// Bounding box.
+} JointDesc;
+
+/// Skeleton descriptor.
+typedef struct SkeletonDesc {
+  size_t    num_joints;
+  joint_idx joints[GFX_MAX_NUM_JOINTS]; /// Indices into Anima's joints array.
+} SkeletonDesc;
+
+/// Animation interpolation mode.
+typedef enum AnimationInterpolation {
+  StepInterpolation,
+  LinearInterpolation,
+  CubicSplineInterpolation
+} AnimationInterpolation;
+
+/// The kind of transformation applied by a Channel.
+typedef enum ChannelType {
+  RotationChannel,
+  ScaleChannel,
+  TranslationChannel,
+  WeightsChannel
+} ChannelType;
+
+/// Animation keyframe descriptor.
+///
+/// The arrays should have as many entries as 'num_joints' in the SkeletonDesc.
+typedef struct KeyframeDesc {
+  R time; // Start time in [0, end animation time]
+  union {
+    vec3 translation;
+    quat rotation;
+  };
+} KeyframeDesc;
+
+/// Animation channel descriptor.
+typedef struct ChannelDesc {
+  joint_idx              target; /// Index into Anima's joints array.
+  ChannelType            type;
+  AnimationInterpolation interpolation;
+  size_t                 num_keyframes;
+  KeyframeDesc           keyframes[GFX_MAX_NUM_KEYFRAMES];
+} ChannelDesc;
+
+/// Animation descriptor.
+typedef struct AnimationDesc {
+  // TODO: Store a name hash for faster comparisons.
+  sstring     name;         // Animation name. Required for playback.
+  size_t      num_channels; // Number of channels.
+  ChannelDesc channels[GFX_MAX_NUM_CHANNELS];
+} AnimationDesc;
+
+/// Anima object descriptor.
+///
+/// The last joint of the joints array at index 'num_joints - 1' must be the
+/// root of all skeletons; specifically, the root of all joints that otherwise
+/// would have no parent (a skeleton need not have its own root and can be a set
+/// of disjoint node hierarchies).
+typedef struct AnimaDesc {
+  size_t        num_skeletons;
+  size_t        num_animations;
+  size_t        num_joints;
+  SkeletonDesc  skeletons[GFX_MAX_NUM_SKELETONS];
+  AnimationDesc animations[GFX_MAX_NUM_ANIMATIONS];
+  JointDesc     joints[GFX_MAX_NUM_JOINTS];
+} AnimaDesc;
+
+/// Animation play settings.
+typedef struct AnimationPlaySettings {
+  const char* name; // Animation name.
+  bool        loop; // Whether to loop the animation or just play once.
+  // TODO: Add animation speed.
+} AnimationPlaySettings;
+
+/// Create an anima object.
+Anima* gfx_make_anima(const AnimaDesc*);
+
+/// Destroy the anima.
+void gfx_destroy_anima(Anima**);
+
+/// Play an animation (sets the current animation).
+bool gfx_play_animation(Anima*, const AnimationPlaySettings*);
+
+/// Update the current animation.
+void gfx_update_animation(Anima*, R t);
+
+/// Stop the current animation.
+void gfx_stop_animation(Anima*);
+
+/// Return the anima's ith skeleton.
+const Skeleton* gfx_get_anima_skeleton(const Anima* anima, size_t i);
+
+/// Return the number of joints in the skeleton.
+size_t gfx_get_skeleton_num_joints(const Skeleton*);
+
+/// Return true if the skeleton's ith joint has a bounding box.
+///
+/// IK joints that do not directly transform vertices have no bounding box.
+bool gfx_joint_has_box(const Anima*, const Skeleton*, size_t joint);
+
+/// Return the bounding box of the skeleton's ith joint.
+///
+/// IK joints that do not directly transform vertices have no box.
+Box gfx_get_joint_box(const Anima*, const Skeleton*, size_t joint);
diff --git a/include/gfx/scene/camera.h b/include/gfx/scene/camera.h
new file mode 100644
index 0000000..99d83fe
--- /dev/null
+++ b/include/gfx/scene/camera.h
@@ -0,0 +1,22 @@
+#pragma once
+
+#include <math/fwd.h>
+
+typedef struct SceneNode SceneNode;
+
+typedef struct SceneCamera SceneCamera;
+
+/// Create a new camera.
+SceneCamera* gfx_make_camera();
+
+/// Destroy the camera.
+///
+/// The camera is conveniently removed from the scene graph and its parent scene
+/// node is destroyed.
+void gfx_destroy_camera(SceneCamera**);
+
+/// Set the scene camera's math camera.
+void gfx_set_camera_camera(SceneCamera* scene_camera, Camera* camera);
+
+/// Get the scene camera's math camera.
+Camera* gfx_get_camera_camera(SceneCamera*);
diff --git a/include/gfx/scene/light.h b/include/gfx/scene/light.h
new file mode 100644
index 0000000..132e344
--- /dev/null
+++ b/include/gfx/scene/light.h
@@ -0,0 +1,30 @@
+#pragma once
+
+typedef struct Texture Texture;
+
+typedef struct Light Light;
+
+/// Light type.
+typedef enum LightType { EnvironmentLightType } LightType;
+
+/// Describes an environment light.
+typedef struct EnvironmentLightDesc {
+  const Texture* environment_map;
+} EnvironmentLightDesc;
+
+/// Describes a light.
+typedef struct LightDesc {
+  LightType type;
+  union {
+    EnvironmentLightDesc environment;
+  } light;
+} LightDesc;
+
+/// Create a light.
+Light* gfx_make_light(const LightDesc*);
+
+/// Destroy the light.
+///
+/// The light is conveniently removed from the scene graph and its parent scene
+/// node is destroyed.
+void gfx_destroy_light(Light**);
diff --git a/include/gfx/scene/material.h b/include/gfx/scene/material.h
new file mode 100644
index 0000000..bca664e
--- /dev/null
+++ b/include/gfx/scene/material.h
@@ -0,0 +1,25 @@
+#pragma once
+
+#include <gfx/core.h>
+#include <gfx/sizes.h>
+
+typedef struct Material Material;
+
+/// Describes a material.
+///
+/// A material holds a shader program and a set of shader-specific uniform
+/// variables. Two materials can share the same shader, but shader parameters
+/// generally give two materials a different appearance.
+typedef struct MaterialDesc {
+  ShaderUniform uniforms[GFX_MAX_UNIFORMS_PER_MATERIAL];
+  int           num_uniforms;
+} MaterialDesc;
+
+/// Create a material.
+Material* gfx_make_material(const MaterialDesc*);
+
+/// Destroy the material.
+///
+/// The caller must make sure that no Mesh points to the given Material.
+/// For a safe purge of unused resources, see scene_purge().
+void gfx_destroy_material(Material**);
diff --git a/include/gfx/scene/mesh.h b/include/gfx/scene/mesh.h
new file mode 100644
index 0000000..0d3b4d4
--- /dev/null
+++ b/include/gfx/scene/mesh.h
@@ -0,0 +1,23 @@
+#pragma once
+
+typedef struct Geometry      Geometry;
+typedef struct Material      Material;
+typedef struct ShaderProgram ShaderProgram;
+
+typedef struct Mesh Mesh;
+
+/// Describes a mesh.
+typedef struct MeshDesc {
+  const Geometry* geometry;
+  const Material* material;
+  ShaderProgram*  shader;
+} MeshDesc;
+
+/// Create a mesh.
+Mesh* gfx_make_mesh(const MeshDesc*);
+
+/// Destroy the mesh.
+///
+/// The caller must make sure that no SceneObject points to the given Mesh.
+/// For a safe purge of unused resources, see scene_purge().
+void gfx_destroy_mesh(Mesh**);
diff --git a/include/gfx/scene/model.h b/include/gfx/scene/model.h
new file mode 100644
index 0000000..42f85d4
--- /dev/null
+++ b/include/gfx/scene/model.h
@@ -0,0 +1,12 @@
+#pragma once
+
+typedef struct Anima     Anima;
+typedef struct Model     Model;
+typedef struct SceneNode SceneNode;
+
+/// Return the model's anima, or null if the model is not animated.
+Anima* gfx_get_model_anima(Model*);
+
+/// Return the model's root node.
+const SceneNode* gfx_get_model_root(const Model*);
+SceneNode*       gfx_get_model_root_mut(Model*);
diff --git a/include/gfx/scene/node.h b/include/gfx/scene/node.h
new file mode 100644
index 0000000..a2c2836
--- /dev/null
+++ b/include/gfx/scene/node.h
@@ -0,0 +1,156 @@
+#pragma once
+
+#include "animation.h"
+
+#include <math/fwd.h>
+#include <math/mat4.h>
+
+#include <stdint.h>
+
+typedef struct Anima       Anima;
+typedef struct Light       Light;
+typedef struct Model       Model;
+typedef struct SceneCamera SceneCamera;
+typedef struct SceneObject SceneObject;
+
+/// Scene node type.
+typedef enum NodeType {
+  LogicalNode,
+  AnimaNode,
+  CameraNode,
+  LightNode,
+  ModelNode,
+  ObjectNode,
+} NodeType;
+
+/// A node in the scene graph.
+///
+/// Scene nodes take ownership of the object they are associated with (Camera,
+/// Light, SceneObject, etc), as well as of child nodes.
+typedef struct SceneNode SceneNode;
+
+// -----------------------------------------------------------------------------
+// Constructors and destructor.
+// -----------------------------------------------------------------------------
+
+/// Create a new scene node.
+///
+/// This node does not contain any camera, light, object, etc. and exists simply
+/// as a logical and spatial construct.
+SceneNode* gfx_make_node();
+
+/// Create an anima node.
+SceneNode* gfx_make_anima_node(Anima*);
+
+/// Create a new camera node.
+SceneNode* gfx_make_camera_node(SceneCamera*);
+
+/// Create a new light node.
+SceneNode* gfx_make_light_node(Light*);
+
+/// Create a new model node.
+SceneNode* gfx_make_model_node(Model*);
+
+/// Create a new object node.
+SceneNode* gfx_make_object_node(SceneObject*);
+
+/// Make the node an anima node.
+void gfx_construct_anima_node(SceneNode*, Anima*);
+
+/// Make the node a camera node.
+void gfx_construct_camera_node(SceneNode*, SceneCamera*);
+
+/// Make the node a light node.
+void gfx_construct_light_node(SceneNode*, Light*);
+
+/// Make the node a model node.
+void gfx_construct_model_node(SceneNode*, Model*);
+
+/// Make the node an object node.
+void gfx_construct_object_node(SceneNode*, SceneObject*);
+
+/// Recursively destroy the scene node and its children.
+///
+/// The scene node and its children are removed from the scene graph.
+///
+/// Node resources -- cameras, lights, objects, etc. -- are also destroyed.
+void gfx_destroy_node(SceneNode**);
+
+// -----------------------------------------------------------------------------
+// Getters.
+// -----------------------------------------------------------------------------
+
+/// Get the node's type.
+NodeType gfx_get_node_type(const SceneNode*);
+
+/// Get the node's anima.
+///
+/// The node must be of type AnimaNode.
+const Anima* gfx_get_node_anima(const SceneNode*);
+Anima*       gfx_get_node_anima_mut(SceneNode*);
+
+/// Get the node's camera.
+///
+/// The node must be of type CameraNode.
+const SceneCamera* gfx_get_node_camera(const SceneNode* node);
+SceneCamera*       gfx_get_node_camera_mut(SceneNode* node);
+
+/// Get the node's light.
+///
+/// The node must be of type LightNode.
+const Light* gfx_get_node_light(const SceneNode*);
+Light*       gfx_get_node_light_mut(SceneNode*);
+
+/// Get the node's model.
+///
+/// The node must be of type ModelNode.
+const Model* gfx_get_node_model(const SceneNode*);
+Model*       gfx_get_node_model_mut(SceneNode*);
+
+/// Get the node's scene object.
+///
+/// The node must be of type ObjectNode.
+const SceneObject* gfx_get_node_object(const SceneNode*);
+SceneObject*       gfx_get_node_object_mut(SceneNode*);
+
+/// Get the node's parent.
+const SceneNode* gfx_get_node_parent(const SceneNode*);
+SceneNode*       gfx_get_node_parent_mut(SceneNode*);
+
+/// Get the node's first child.
+const SceneNode* gfx_get_node_child(const SceneNode*);
+SceneNode*       gfx_get_node_child_mut(SceneNode*);
+
+/// Get the node's immediate sibling.
+const SceneNode* gfx_get_node_sibling(const SceneNode*);
+SceneNode*       gfx_get_node_sibling_mut(SceneNode*);
+
+/// Get the node's (local) transform.
+mat4 gfx_get_node_transform(const SceneNode*);
+
+/// Get the node's global transform.
+mat4 gfx_get_node_global_transform(const SceneNode*);
+
+// -----------------------------------------------------------------------------
+// Setters.
+// -----------------------------------------------------------------------------
+
+/// Set the node's parent.
+///
+/// Pass in null to unwire from the existing parent, if one exists.
+void gfx_set_node_parent(SceneNode*, SceneNode* parent_node);
+
+/// Set the node's (local) transform.
+void gfx_set_node_transform(SceneNode*, const mat4* transform);
+
+/// Set the node's position.
+void gfx_set_node_position(SceneNode*, const vec3* position);
+
+/// Set the node's rotation.
+void gfx_set_node_rotation(SceneNode*, const quat* rotation);
+
+/// Set the node's rotation.
+void gfx_set_node_rotation_mat(SceneNode*, const mat4* rotation);
+
+/// Log the node's hierarchy.
+void gfx_log_node_hierarchy(const SceneNode*);
diff --git a/include/gfx/scene/object.h b/include/gfx/scene/object.h
new file mode 100644
index 0000000..7579d29
--- /dev/null
+++ b/include/gfx/scene/object.h
@@ -0,0 +1,39 @@
+#pragma once
+
+#include <gfx/sizes.h>
+
+#include <math/fwd.h>
+
+#include <math/aabb3.h>
+
+typedef struct Mesh      Mesh;
+typedef struct SceneNode SceneNode;
+typedef struct Skeleton  Skeleton;
+
+typedef struct SceneObject SceneObject;
+
+typedef struct ObjectDesc {
+  size_t num_meshes;
+  Mesh*  meshes[GFX_MAX_NUM_MESHES];
+} ObjectDesc;
+
+/// Create a new object.
+SceneObject* gfx_make_object(const ObjectDesc*);
+
+/// Destroy the object.
+///
+/// The object is conveniently removed from the scene graph and its parent scene
+/// node is destroyed.
+void gfx_destroy_object(SceneObject**);
+
+/// Set the object's skeleton.
+void gfx_set_object_skeleton(SceneObject*, const Skeleton*);
+
+/// Get the object's skeleton.
+/// Return null if the object has no skeleton.
+const Skeleton* gfx_get_object_skeleton(const SceneObject*);
+
+/// Gets the object's bounding box.
+///
+/// The object's bounding box is the bounding box of its mesh geometries.
+aabb3 gfx_get_object_aabb(const SceneObject*);
diff --git a/include/gfx/scene/scene.h b/include/gfx/scene/scene.h
new file mode 100644
index 0000000..0d96210
--- /dev/null
+++ b/include/gfx/scene/scene.h
@@ -0,0 +1,21 @@
+#pragma once
+
+#include <math/defs.h>
+#include <math/fwd.h>
+
+typedef struct SceneNode SceneNode;
+
+typedef struct Scene Scene;
+
+/// Create a new scene.
+Scene* gfx_make_scene(void);
+
+/// Destroy the scene.
+///
+/// This function destroys the scene and all objects that it owns (scene
+/// objects, cameras, lights, etc), but not objects that could be shared with
+/// other scenes (meshes, materials, etc).
+void gfx_destroy_scene(Scene**);
+
+/// Get the scene's root node.
+SceneNode* gfx_get_scene_root(Scene*);
diff --git a/include/gfx/sizes.h b/include/gfx/sizes.h
new file mode 100644
index 0000000..076113c
--- /dev/null
+++ b/include/gfx/sizes.h
@@ -0,0 +1,95 @@
+/// Size constants used throughout the library.
+#pragma once
+
+// Scene.
+
+/// Maximum number of cameras per scene.
+#define GFX_MAX_NUM_CAMERAS 16
+
+/// Maximum number of lights.
+#define GFX_MAX_NUM_LIGHTS 1024
+
+/// Maximum number of materials.
+#define GFX_MAX_NUM_MATERIALS 1024
+
+/// Maximum number of meshes.
+#define GFX_MAX_NUM_MESHES 1024
+
+/// Maximum number of mesh links.
+#define GFX_MAX_NUM_MESH_LINKS 1024
+
+/// Maximum number of models.
+#define GFX_MAX_NUM_MODELS 64
+
+/// Maximum number of joints per skeleton.
+#define GFX_MAX_NUM_JOINTS 96
+
+/// Maximum number of keyframes per channel.
+#define GFX_MAX_NUM_KEYFRAMES 32
+
+/// Maximum number of channels per animation.
+#define GFX_MAX_NUM_CHANNELS 128
+
+/// Maximum number of skeletons.
+#define GFX_MAX_NUM_SKELETONS 128
+
+/// Maximum number of animations.
+#define GFX_MAX_NUM_ANIMATIONS 128
+
+/// Maximum number of animas.
+#define GFX_MAX_NUM_ANIMAS 128
+
+/// Maximum number of nodes per scene.
+#define GFX_MAX_NUM_NODES 1024
+
+/// Maximum number of objects per scene.
+#define GFX_MAX_NUM_OBJECTS 1024
+
+/// Maximum number of uniforms in a Material.
+#define GFX_MAX_UNIFORMS_PER_MATERIAL 18
+
+// Render.
+
+/// Maximum number of buffers per renderer.
+#define GFX_MAX_NUM_BUFFERS 1024
+
+/// Maximum number of framebuffers per renderer.
+#define GFX_MAX_NUM_FRAMEBUFFERS 32
+
+/// Maximum number of geometries per renderer.
+#define GFX_MAX_NUM_GEOMETRIES 1024
+
+/// Maximum number of renderbuffers per renderer.
+#define GFX_MAX_NUM_RENDERBUFFERS (GFX_MAX_NUM_FRAMEBUFFERS * 2)
+
+/// Maximum number of shader programs per renderer.
+#define GFX_MAX_NUM_SHADER_PROGRAMS 128
+
+/// Maximum number of shaders per renderer.
+#define GFX_MAX_NUM_SHADERS (GFX_MAX_NUM_SHADER_PROGRAMS * 2)
+
+/// Maximum number of textures per renderer.
+#define GFX_MAX_NUM_TEXTURES 1024
+
+/// Maximum number of uniforms in a ShaderProgram.
+#define GFX_MAX_UNIFORMS_PER_SHADER (GFX_MAX_UNIFORMS_PER_MATERIAL + 8)
+
+/// Maximum number of compiler defines in a Shader.
+#define GFX_MAX_SHADER_COMPILER_DEFINES 16
+
+// Renderer.
+
+/// Maximum number of triangles that the immediate-mode renderer can draw in a
+/// frame.
+#define IMM_MAX_NUM_TRIANGLES 1024
+
+/// Maximum number of matrices in the immediate-mode renderer's matrix stack.
+#define IMM_MAX_NUM_MATRICES 32
+
+// Asset Manager.
+
+#define GFX_MAX_NUM_ASSETS 1024
+
+// Gfx.
+
+#define GFX_MAX_NUM_SCENES 4
diff --git a/include/gfx/util/geometry.h b/include/gfx/util/geometry.h
new file mode 100644
index 0000000..a962291
--- /dev/null
+++ b/include/gfx/util/geometry.h
@@ -0,0 +1,13 @@
+/// Functions to construct geometry procedurally.
+#pragma once
+
+#include <gfx/core.h>
+
+#include <math/vec2.h>
+#include <math/vec3.h>
+
+/// Construct a quad with positions in the range [-1, 1]^2.
+Geometry* gfx_make_quad_11(GfxCore*);
+
+/// Construct a quad with positions in the range [0, 1]^2.
+Geometry* gfx_make_quad_01(GfxCore*);
diff --git a/include/gfx/util/ibl.h b/include/gfx/util/ibl.h
new file mode 100644
index 0000000..6e39180
--- /dev/null
+++ b/include/gfx/util/ibl.h
@@ -0,0 +1,25 @@
+/// Functions for image-based lighting.
+#pragma once
+
+typedef struct IBL IBL;
+
+typedef struct GfxCore GfxCore;
+typedef struct Texture Texture;
+
+/// Create an environment map filterer for IBL.
+IBL* gfx_make_ibl(GfxCore*);
+
+/// Destroy the environment map filterer.
+void gfx_destroy_ibl(GfxCore*, IBL**);
+
+/// Create a BRDF integration map for IBL.
+Texture* gfx_make_brdf_integration_map(IBL*, GfxCore*, int width, int height);
+
+/// Create an irradiance map (cubemap) from an environment map for IBL.
+Texture* gfx_make_irradiance_map(
+    IBL*, GfxCore*, const Texture* environment_map, int width, int height);
+
+/// Create a prefiltered environment map (cubemap) for IBL.
+Texture* gfx_make_prefiltered_environment_map(
+    IBL*, GfxCore*, const Texture* environment_map, int width, int height,
+    int* max_mip_level);
diff --git a/include/gfx/util/shader.h b/include/gfx/util/shader.h
new file mode 100644
index 0000000..bd058f4
--- /dev/null
+++ b/include/gfx/util/shader.h
@@ -0,0 +1,46 @@
+/// A variety of shaders included for convenience.
+#pragma once
+
+#include <stddef.h>
+
+typedef struct GfxCore              GfxCore;
+typedef struct ShaderCompilerDefine ShaderCompilerDefine;
+typedef struct ShaderProgram        ShaderProgram;
+
+/// Create a BRDF integration map shader.
+ShaderProgram* gfx_make_brdf_integration_map_shader(GfxCore*);
+
+/// Create a Cook-Torrance shader.
+ShaderProgram* gfx_make_cook_torrance_shader(GfxCore*);
+
+/// Create a Cook-Torrance shader with additional shader compiler defines.
+/// This function can be used to create shader permutations.
+ShaderProgram* gfx_make_cook_torrance_shader_perm(
+    GfxCore*, const ShaderCompilerDefine*, size_t num_defines);
+
+/// Create a 3D debugging shader.
+ShaderProgram* gfx_make_debug3d_shader(GfxCore*);
+
+/// Create a shader for drawing in immediate mode.
+ShaderProgram* gfx_make_immediate_mode_shader(GfxCore*);
+
+/// Create a shader for computing irradiance maps from cube maps.
+ShaderProgram* gfx_make_irradiance_map_shader(GfxCore*);
+
+/// Create a shader for computing prefiltered environment maps from cube maps.
+ShaderProgram* gfx_make_prefiltered_environment_map_shader(GfxCore*);
+
+/// Create a skyquad shader.
+ShaderProgram* gfx_make_skyquad_shader(GfxCore*);
+
+/// Create a shader to view normal-mapped normals.
+ShaderProgram* gfx_make_view_normal_mapped_normals_shader(GfxCore*);
+
+/// Create a shader to view vertex normals.
+ShaderProgram* gfx_make_view_normals_shader(GfxCore*);
+
+/// Create a shader to view vertex tangents.
+ShaderProgram* gfx_make_view_tangents_shader(GfxCore*);
+
+/// Create a shader to view textures.
+ShaderProgram* gfx_make_view_texture_shader(GfxCore*);
diff --git a/include/gfx/util/skyquad.h b/include/gfx/util/skyquad.h
new file mode 100644
index 0000000..2b3fe17
--- /dev/null
+++ b/include/gfx/util/skyquad.h
@@ -0,0 +1,22 @@
+/// A skyquad is like a skybox but with a single quad.
+#pragma once
+
+typedef struct GfxCore     GfxCore;
+typedef struct Scene       Scene;
+typedef struct SceneNode   SceneNode;
+typedef struct SceneObject SceneObject;
+typedef struct Texture     Texture;
+
+/// Create a skyquad.
+SceneObject* gfx_make_skyquad(GfxCore*, const Texture*);
+
+/// Set up a skyquad in the scene.
+///
+/// This function adds two scene nodes under the given root node:
+///   - An object node to render the skyquad in the background.
+///   - A light node to light up other objects with the skyquad.
+///
+/// Return the light node under which objects affected by the light can be
+/// rooted.
+SceneNode* gfx_setup_skyquad(
+    GfxCore*, SceneNode* root, const Texture* environment_map);