Method on_draw

samples/gl-debug-ui/gl-debug-ui.cpp:190–302

}

void sample_gl_debug_ui::on_draw()
{
    glfwMakeContextCurrent(window);

    int width, height;
    glfwGetWindowSize(window, &width, &height);

    glViewport(0, 0, width, height);
    glClearColor(0.25f, 0.25f, 0.25f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glEnable(GL_CULL_FACE);
    glEnable(GL_DEPTH_TEST);

    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    const float4x4 projectionMatrix = cam.get_projection_matrix(float(width) / float(height));
    const float4x4 viewMatrix = cam.get_view_matrix();
    const float4x4 viewProjectionMatrix = (projectionMatrix * viewMatrix);

    // Render the offscreen nvg surface
    {
        std::string text = "Polymer Engine";

        NVGcontext * nvg = surface->pre_draw(window, 0);
        const float2 size = surface->surface_size();

        nvgSave(nvg);

        nvgBeginPath(nvg);
        nvgRect(nvg, 0, 0, size.x, size.y);
        nvgFillColor(nvg, nvgRGBAf(0.2f, 0.2f, 0.2f, 1.f));
        nvgFill(nvg);

        surface->draw_text_quick(text, 120, float2(size.x / 2, size.y / 2), nvgRGBAf(1, 1, 1, 1));

        nvgRestore(nvg);

        surface->post_draw();
    }

    // Reset state changed by nanovg
    glViewport(0, 0, width, height);
    glEnable(GL_DEPTH_TEST);

    const float4x4 boxModel = (make_translation_matrix({ 0, 6, -10 }) * make_scaling_matrix(float3(8.f, 4.f, 0.1f)));

    // Render the offscreen nvg surface in the world as a small quad to the left
    {
        const float4x4 nvgSurfaceModel = (make_translation_matrix({ -4, 2, 0 }) * make_rotation_matrix({ 0, 1, 0 }, (float)POLYMER_PI / 2.f));
        nvg_surface_shader.bind();
        nvg_surface_shader.uniform("u_mvp", (viewProjectionMatrix * nvgSurfaceModel));
        nvg_surface_shader.texture("s_texture", 0, surface->surface_texture(0), GL_TEXTURE_2D);
        quad_mesh.draw_elements();
        nvg_surface_shader.unbind();
    }