void clear_window(v3 color)
{
	glClearColor(color.x, color.y, color.z, 1.0f);
	glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
}

void begin3d(prge_window_t window, shader_t shader, camera_t camera)
{
	f32 aspect_ratio = (f32)window.width/(f32)window.height;
	mat4 projection = perspective(camera, aspect_ratio);
	mat4 view = camera_get_view_mat(camera);

	glUseProgram(shader.id);
	shader_set_mat4(shader, SHADER_PROJECTION_MATRIX, projection);
	shader_set_mat4(shader, SHADER_VIEW_MATRIX, view);
}

void end3d(void)
{
	glUseProgram(0);
}

void begin3d_alpha(prge_window_t window, shader_t shader, camera_t camera)
{
	glEnable(GL_BLEND);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	begin3d(window, shader, camera);
}

void end3d_alpha(void)
{
	end3d();
	glDisable(GL_BLEND);
}

void draw_mesh(mesh_t mesh)
{
	if (!mesh.vao) {
		printf("warning: trying to draw mesh that doesn't have vao\n");
		return;
	}

	glBindVertexArray(mesh.vao);

	for (i32 i = 0; i < mesh.ntextures; i++) {
		glActiveTexture(GL_TEXTURE0+i);
		glBindTexture(GL_TEXTURE_2D, mesh.textures[i].id);
	}

	if (mesh.ebo)
		glDrawElements(GL_TRIANGLES, mesh.nindices, GL_UNSIGNED_INT, 0);
	else
		glDrawArrays(GL_TRIANGLES, 0, mesh.nvertices);

	glBindTexture(GL_TEXTURE_2D, 0);

	glBindVertexArray(0);
} 

void draw_model(shader_t shader, model_t model)
{
	mat4 modelmat = apply_transform(model.transform);
	for (i32 i = 0; i < model.nmeshes; ++i) {
		mat4 meshmat = apply_transform(model.meshes[i].transform);
		mat4 resultmat = mat4_mul(modelmat, meshmat);

		shader_set_mat4(shader, SHADER_MODEL_MATRIX, resultmat);
		draw_mesh(model.meshes[i]);
	}
}

void draw_entity(shader_t shader, entity_t entity)
{
	v3 position = entity.model.transform.position;
	position = v3_add(position, entity.position);
	entity.model.transform.position = position;
	draw_model(shader, entity.model);
}

void draw_entities(elist_t entities, shader_t shader)
{
	for (enode_t *node = entities.first; node; node = node->next)
		if (!(node->entity.flags & ENTITY_ALPHA))
			draw_entity(shader, node->entity);
}

void draw_entities_alpha(elist_t entities, shader_t shader)
{
	for (enode_t *node = entities.first; node; node = node->next)
		if (node->entity.flags & ENTITY_ALPHA)
			draw_entity(shader, node->entity);
}