Huge changes for 3d

engine/src/shaders/sprite.vert

@@ -22,10 +22,8 @@ void main() {
   vec2 corner = CORNERS[gl_VertexIndex];
 
   gl_Position = push.viewProjection * model * vec4(corner, 0.0, 1.0);
-  // Draw order comes from the CPU-side sort, so flatten depth; sprites should
-  // never be clipped by the camera's near/far planes.
-  gl_Position.z = 0.0;
 
   fragColor = color;
-  fragUv = mix(uvRect.xy, uvRect.zw, corner);
+  // The quad's y runs up and the texture's v runs down.
+  fragUv = mix(uvRect.xy, uvRect.zw, vec2(corner.x, 1.0 - corner.y));
 }