Decoupling renderer framerate from occlusion query framerate.

r_occlude.c

/**
 * @brief Updates and re-draws active occlusion queries for the current frame.
 */
void R_UpdateOcclusionQueries(r_view_t *view) {

	if (!r_occlude->integer) {
		return;
	}

	if (view->flags & VIEW_FLAG_NO_DELTA) {
		view->num_occlusion_queries = r_occlusion.num_queries = 0;
	}

	glEnable(GL_DEPTH_TEST);
	glEnable(GL_CULL_FACE);

	glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
	glDepthMask(GL_FALSE);

	glUseProgram(r_depth_pass_program.name);

	glBindVertexArray(r_occlusion.vertex_array);
	glEnableVertexAttribArray(r_depth_pass_program.in_position);

	glBindBuffer(GL_ARRAY_BUFFER, r_occlusion.vertex_buffer);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, r_occlusion.elements_buffer);

	const GLsizei size = sizeof(r_occlusion.vertexes[0]) * r_occlusion.num_queries;
	glBufferSubData(GL_ARRAY_BUFFER, 0, size, r_occlusion.vertexes);

	for (int32_t i = 0; i < view->num_occlusion_queries; i++) {

		r_occlusion_query_t *q = view->occlusion_queries[i];

		if (!q->available) {
			glGetQueryObjectiv(q->name, GL_QUERY_RESULT_AVAILABLE, &q->available);
			if (q->available || r_occlude->integer == 2) {
				glGetQueryObjectiv(q->name, GL_QUERY_RESULT, &q->result);
			}
		}

		if (q->available) {
			glBeginQuery(GL_ANY_SAMPLES_PASSED, q->name);
			glDrawElementsBaseVertex(GL_TRIANGLES, 36, GL_UNSIGNED_INT, NULL, q->index * 8);
			glEndQuery(GL_ANY_SAMPLES_PASSED);
			q->available = 0;
		}
	}

	glBindBuffer(GL_ARRAY_BUFFER, 0);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);

	glBindVertexArray(0);

	glDepthMask(GL_TRUE);
	glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);

	glDisable(GL_CULL_FACE);
	glDisable(GL_DEPTH_TEST);

	R_GetError(NULL);
}