Question

有没有人有PBO（像素缓冲对象）+ SDL2.0（简单直接媒体层）+ OpenGL的工作示例？

原因是获得异步GPU - ＆gt;使用GLGetPixels下载CPU，从而提高性能。

这是我的尝试。 use_pbo = false或true没有任何测量差异。我之前在同一台机器上使用过带有GLUT的PBO，所以我知道我的硬件支持它。

我在http://www.songho.ca/opengl/gl_pbo.html教程中看了很多，但没看到我做错了什么。

bool use_pbo = true; //remember to wait a bit for fps to pick up speed

if(SDL_Init(SDL_INIT_EVENTS) != 0) throw "SDL_Init";

SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);

sdl_window = SDL_CreateWindow("", 10, 20, window_width, window_height, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);

sdl_gl_context = SDL_GL_CreateContext(sdl_window);
SDL_GL_MakeCurrent(sdl_window, sdl_gl_context);

vertical_sync(false);

{
    glGenBuffers(2, pbos);
    glBindBuffer(GL_PIXEL_PACK_BUFFER, pbos[0]);
    glBufferData(GL_PIXEL_PACK_BUFFER, pbo_width*pbo_height*4, 0, GL_STREAM_READ);

    glBindBuffer(GL_PIXEL_PACK_BUFFER, pbos[1]);
    glBufferData(GL_PIXEL_PACK_BUFFER, pbo_width*pbo_height*4, 0, GL_STREAM_READ);

    glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
}

//render to default frame buffer
{
    glDrawBuffer(GL_BACK);

    glClearColor(0.1, 0.2, 0.3, 0);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

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

    glUseProgram(simple_shader);

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, transparent_texture);

    glBegin(GL_TRIANGLE_STRIP);
    //textcoord, color, position
    glVertexAttrib2f(2, 0, 1); glVertexAttrib4f(1, 1, 0, 0, 1); glVertexAttrib2f(0, -1, -1); //bottom left
    glVertexAttrib2f(2, 1, 1); glVertexAttrib4f(1, 0, 1, 0, 1); glVertexAttrib2f(0, +1, -1); //bottom right
    glVertexAttrib2f(2, 0, 0); glVertexAttrib4f(1, 0, 0, 1, 1); glVertexAttrib2f(0, -1, +1); //top left
    glVertexAttrib2f(2, 1, 0); glVertexAttrib4f(1, 1, 1, 0, 1); glVertexAttrib2f(0, +1, +1); //top right
    glEnd();

    glBindTexture(GL_TEXTURE_2D, 0);

    glUseProgram(0);

    glDisable(GL_BLEND);

    while(true)
    {
        if(use_pbo)
        {
            glBindBuffer(GL_PIXEL_PACK_BUFFER, pbos[1]);
            GLvoid* map_buffer_data = glMapBuffer(GL_PIXEL_PACK_BUFFER, GL_READ_ONLY);

            if(map_buffer_data)
            {
                //glRasterPos2i(-1, -1); //default, left bottom
                glRasterPos2i(0, -1);
                glDrawPixels(pbo_width, pbo_height, GL_BGRA, GL_UNSIGNED_BYTE, map_buffer_data);
                glUnmapBuffer(GL_PIXEL_PACK_BUFFER);
            }

            glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
        }
        else
        {       
            glRasterPos2i(0, -1); //right bottom
            glDrawPixels(pbo_width, pbo_height, GL_BGRA, GL_UNSIGNED_BYTE, t.c);
        }
    }
}

SDL_GL_SwapWindow(sdl_window);

//cycle buffers
{
    GLuint t = pbos[1];
    pbos[1] = pbos[0];
    pbos[0] = t;
}

Answer 1

尝试将PBO绑定到纹理

GL_PIXEL_UNPACK_BUFFER用于传递到OpenGL GL_PIXEL_PACK_BUFFER的像素数据，用于从OpenGL 检索的像素数据

您还应该使用glTexImage2D

定义纹理图像

如果非零命名缓冲区对象绑定到GL_PIXEL_UNPACK_BUFFER目标（见glBindBuffer）纹理图像是指定的数据被视为缓冲区对象的数据存储中的字节偏移量。

有没有人有PBO + SDL2.0 + OpenGL的例子

1 个答案: