Fix camera rotation

Ensure rotation and scale happen after translation, and from the center of the camera.

Fixes grimfang4#133 and grimfang4#124

src/renderer_GL_common.inl

@@ -1191,24 +1191,27 @@ static void changeCamera(GPU_Target* target)
 
 static void get_camera_matrix(GPU_Target* target, float* result)
 {
-	float offsetX, offsetY;
+    float offsetX, offsetY;
 
     GPU_MatrixIdentity(result);
 
-    GPU_MatrixTranslate(result, -target->camera.x, -target->camera.y, -target->camera.z);
-
     if(target->camera.use_centered_origin)
     {
         offsetX = target->w/2.0f;
         offsetY = target->h/2.0f;
         GPU_MatrixTranslate(result, offsetX, offsetY, 0);
     }
 
+    // Always rotate from the camera center
     GPU_MatrixRotate(result, target->camera.angle, 0, 0, 1);
-    GPU_MatrixScale(result, target->camera.zoom_x, target->camera.zoom_y, 1.0f);
 
     if(target->camera.use_centered_origin)
         GPU_MatrixTranslate(result, -offsetX, -offsetY, 0);
+
+    GPU_MatrixTranslate(result, -target->camera.x, -target->camera.y, -target->camera.z);
+
+    GPU_MatrixScale(result, target->camera.zoom_x, target->camera.zoom_y, 1.0f);
+
 }