Function draw

source/examples/transformfeedback/main.cpp:134–175

}

void draw()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    const auto side = std::min<int>(g_size.x, g_size.y);
    glViewport((g_size.x - side) / 2, (g_size.y - side) / 2, side, side);

    const auto t_elapsed = std::chrono::high_resolution_clock::now() - g_startTime;
    g_startTime = std::chrono::high_resolution_clock::now();

    auto drawBuffer  = g_vertexBuffer1;
    auto writeBuffer = g_vertexBuffer2;

    g_vao->bind();

    g_transformFeedbackProgram->setUniform("deltaT", static_cast<float>(t_elapsed.count()) * float(std::nano::num) / float(std::nano::den));

    g_vao->binding(0)->setBuffer(drawBuffer, 0, sizeof(glm::vec4));

    g_transformFeedback->bind();
    writeBuffer->bindBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0);

    glEnable(GL_RASTERIZER_DISCARD);

    g_transformFeedbackProgram->use();
    g_transformFeedback->begin(GL_TRIANGLES);
    g_vao->drawArrays(GL_TRIANGLES, 0, 6);
    g_transformFeedback->end();
    glDisable(GL_RASTERIZER_DISCARD);

    g_transformFeedback->unbind();

    g_vao->binding(0)->setBuffer(writeBuffer, 0, sizeof(glm::vec4));

    g_shaderProgram->use();
    g_transformFeedback->draw(GL_TRIANGLE_STRIP);
    g_shaderProgram->release();

    g_vao->unbind();

    std::swap(g_vertexBuffer1, g_vertexBuffer2);
}


void error(int errnum, const char * errmsg)