Question

我正在尝试测试如何在笔记本电脑上绘制三角形，因此在系统上执行以下操作：

操作系统：Windows 10 处理器：Intel Core i5 5200U GPU：NVIDIA Geforce 820M

代码：

glfwWindowHint(GLFW_SAMPLES, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // To make MacOS happy; should not be needed
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

// Open a window and create its OpenGL context

window = glfwCreateWindow( 1024, 768, "Tutorial 02 - Red triangle", NULL, NULL);
if( window == NULL ){
    fprintf( stderr, "Failed to open GLFW window. If you have an Intel GPU, they are not 3.3 compatible. Try the 2.1 version of the tutorials.\n" );
    getchar();
    glfwTerminate();
    return -1;
}
glfwMakeContextCurrent(window);

// Initialize GLEW
glewExperimental = true; // Needed for core profile
if (glewInit() != GLEW_OK) {
    fprintf(stderr, "Failed to initialize GLEW\n");
    getchar();
    glfwTerminate();
    return -1;
}

// Ensure we can capture the escape key being pressed below
glfwSetInputMode(window, GLFW_STICKY_KEYS, GL_TRUE);

// Dark blue background
glClearColor(0.0f, 0.0f, 0.4f, 0.0f);

GLuint VertexArrayID;
glGenVertexArrays(1, &VertexArrayID);
glBindVertexArray(VertexArrayID);

// Create and compile our GLSL program from the shaders
GLuint programID = LoadShaders( "SimpleVertexShader.vertexshader", "SimpleFragmentShader.fragmentshader" );


// Number of triangles
const int v = 200;
static  GLfloat g_vertex_buffer_data[v*9] = { 
    -1.0f, -1.0f, 1.0f,
     0.8f, 0.f, 0.0f,
     0.5f,  1.0f, 0.0f,
};

// fill buffer of triangles
for (int i = 9; i < v * 9; i += 9)
{
    g_vertex_buffer_data[i] = g_vertex_buffer_data[0];
    g_vertex_buffer_data[i+1] = g_vertex_buffer_data[1];
    g_vertex_buffer_data[i+2] = g_vertex_buffer_data[2];

    g_vertex_buffer_data[i+3] = g_vertex_buffer_data[3];
    g_vertex_buffer_data[i+4] = g_vertex_buffer_data[4];
    g_vertex_buffer_data[i+5] = g_vertex_buffer_data[5];

    g_vertex_buffer_data[i+6] = g_vertex_buffer_data[6];
    g_vertex_buffer_data[i+7] = g_vertex_buffer_data[7];
    g_vertex_buffer_data[i+8] = g_vertex_buffer_data[8];
}

GLuint vertexbuffer;
glGenBuffers(1, &vertexbuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW);

int frameNr = 0;
char text[100];
do{

    // Clear the screen
    glClear( GL_COLOR_BUFFER_BIT );

    // Use our shader
    glUseProgram(programID);

    // 1rst attribute buffer : vertices
    glEnableVertexAttribArray(0);
    glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
    glVertexAttribPointer(
        0,                  // attribute 0. No particular reason for 0, but must match the layout in the shader.
        3,                  // size
        GL_FLOAT,           // type
        GL_FALSE,           // normalized?
        0,                  // stride
        (void*)0            // array buffer offset
    );

    // Draw the triangle !
    glDrawArrays(GL_TRIANGLES, 0, v*3); // 3 indices starting at 0 -> 1 triangle

    glDisableVertexAttribArray(0);

    // Swap buffers
    glfwSwapBuffers(window);
    glfwPollEvents();
    //glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW);

    frameNr++;
    sprintf_s(text, "%d %d %d", frameNr, clock() / 1000, (frameNr * 1000) / (clock() + 1));
    glfwSetWindowTitle(window, text);

} // Check if the ESC key was pressed or the window was closed
while( glfwGetKey(window, GLFW_KEY_ESCAPE ) != GLFW_PRESS &&
       glfwWindowShouldClose(window) == 0 );

// Cleanup VBO
glDeleteBuffers(1, &vertexbuffer);
glDeleteVertexArrays(1, &VertexArrayID);
glDeleteProgram(programID);

// Close OpenGL window and terminate GLFW
glfwTerminate();

return 0;

令我惊讶的是，在v = 200三角形的情况下，我只能得到约80 fps。这大约是每秒16000个三角形，这是不是很糟糕？

代码中我在做什么错？或者我的图形卡真的可以处理这么少的三角形吗？

一个现代的GPU可以像1080ti一样处理多少个三角形（理论上我听说有110亿个三角形-尽管我知道实际上它要低得多）。

Answer 1

由于我的声誉尚不足以发表评论，因此我在这里问：您的三角形有多大？没有看到顶点着色器很难说清楚，但是假设代码中的那些坐标直接映射到规范化的设备坐标，则三角形覆盖了屏幕的很大一部分。如果我没记错的话，您基本上会在自身上方一遍又一遍地绘制相同的三角形。因此，很可能会限制您的填充率。为了获得更有意义的结果，您可能希望只绘制不重叠三角形的网格，或者至少绘制一个随机三角形汤。为了进一步最小化填充率和帧缓冲带宽要求，您可能想要确保深度缓冲和混合功能已关闭。

如果您对每秒的原始三角形感兴趣，为什么要启用MSAA？这样做只是人为地放大了光栅化器的负载。正如其他人也指出的那样，V-Sync可能会关闭，因为80 Hz的刷新频率相当奇怪，但是最好确保并通过glfwSwapInterval(0)明确将其关闭。与其像估计那样估计总帧时间，不如考虑使用GL_TIME_ELAPSED query测量GPU上的实际绘制时间。

Opengl三角形基准

1 个答案: