Rotate vertices into correct UV space for each image (#8539)

engine/gamesys/src/gamesys/components/comp_sprite.cpp

@@ -1061,25 +1061,33 @@ namespace dmGameSystem
 
  for (uint32_t j = 0; j < num_vertices; ++j, vertices += step)
  {
+ // local coordinates in range [-0.5, 0.5]
+ // No need to rotate these, instead we transform these vertices into correct uv space for each image
  float px = vertices[0];
  float py = vertices[1];
 
- float u = (center_x + px * image_width) / width;
- float v = (center_y + -py * image_height) / height;
+ // local coordinates in range ([-image_width, image_width], [-image_height, image_height])
+ float ix = px;
+ float iy = py;
+
+ // A rotated image is stored with a 90 deg CW rotation
+ // so we need to convert the vertices into the uv space of that image
+ if (rotated) // rotate 90 degrees CW
+ {
+ float t = iy;
+ iy = -ix;
+ ix = t;
+ }
+
+ float u = (center_x + ix * image_width) / width;
+ float v = (center_y + -iy * image_height) / height;
 
  uvs[j*2+0] = u;
  uvs[j*2+1] = 1.0f - v;
 
  // We grab the geometry as positions from the first texture
  if (i == 0)
  {
- if (rotated) // rotate 90 degrees (CCW)
- {
- float t = py;
- py = px;
- px = -t;
- }
-
  (*scratch_pos)[j*2+0] = px * scale_x;
  (*scratch_pos)[j*2+1] = py * scale_y;
  }