Implement camera clipping for ortho maps

1 files changed, 44 insertions, 7 deletions

diff --git a/src/gfx2d.c b/src/gfx2d.c
index f609c98..f1f26cb 100644
--- a/src/gfx2d.c
+++ b/src/gfx2d.c
@@ -20,6 +20,12 @@
 /// Time between animation updates.
 #define ANIMATION_UPDATE_DELTA (1.0 / ANIMATION_FPS)
 
+/// Take the maximum of two values.
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+/// Take the minimum of two values.
+#define min(a, b) ((a) < (b) ? (a) : (b))
+
 typedef struct ivec2 {
   int x, y;
 } ivec2;
@@ -565,7 +571,6 @@ static void draw_rect(
 
   // Rect origin can be outside screen bounds, so we must offset accordingly to
   // draw only the visible portion.
-#define max(a, b) (a > b ? a : b)
   const int px_offset = max(0, -top_left.x);
   const int py_offset = max(0, -top_left.y);
 
@@ -763,13 +768,11 @@ static void draw_sprites(Gfx2d* gfx) {
   }
 }
 
-void gfx2d_set_camera(Gfx2d* gfx, int x, int y) {
-  assert(gfx);
-  gfx->camera = (ivec2){x, y};
-}
-
-void gfx2d_render(Gfx2d* gfx) {
+void gfx2d_render(Gfx2d* gfx, int camera_x, int camera_y) {
   assert(gfx);
+  // Storing the camera mostly for debugging convenience. It could otherwise be
+  // passed around.
+  gfx->camera = (ivec2){camera_x, camera_y};
   draw_map(gfx);
   draw_sprites(gfx);
 }
@@ -789,6 +792,40 @@ void gfx2d_draw_tile(Gfx2d* gfx, int x, int y, Tile tile) {
   }
 }
 
+static void clip_camera_ortho(const Gfx2d* gfx, float* x, float* y) {
+  assert(gfx);
+  assert(gfx->map);
+
+  if (x != nullptr) {
+    const int width_pixels = gfx->map->world_width * gfx->map->base_tile_width;
+    const int x_max        = width_pixels - gfx->screen.width;
+    *x                     = min((float)x_max, max(0.F, *x));
+  }
+  if (y != nullptr) {
+    const int height_pixels =
+        gfx->map->world_height * gfx->map->base_tile_height;
+    const int y_max = height_pixels - gfx->screen.height;
+    *y              = min((float)y_max, max(0.F, *y));
+  }
+}
+
+void gfx2d_clip_camera(const Gfx2d* gfx, float* x, float* y) {
+  assert(gfx);
+  assert(gfx->map);
+  assert(x);
+  assert(y);
+
+  const Tm_Flags* flags = (const Tm_Flags*)&gfx->map->flags;
+  switch (flags->orientation) {
+  case Tm_Orthogonal:
+    clip_camera_ortho(gfx, x, y);
+    break;
+  case Tm_Isometric:
+    // TODO: Clip camera in isometric maps.
+    break;
+  }
+}
+
 void gfx2d_get_screen_size(const Gfx2d* gfx, int* width, int* height) {
   assert(gfx);
   assert(width);