Run shadow render pass and compute light position in vertex shaders

gpu.h

@@ -74,7 +74,7 @@ void gpu_model_load(
 void gpu_model_cleanup(const gpu_ctx_t *ctx, const gpu_model_t *model);
 
 void gpu_render(
-    const gpu_ctx_t *ctx, mat4_t vp, size_t model_count,
+    const gpu_ctx_t *ctx, mat4_t vp, mat4_t light_vp, size_t model_count,
     const gpu_model_t *models, const mat4_t **bone_matrices,
     const mat4_t *model_transforms);