Question

我使用OpenGL和GLSL着色器编写了一个小型OpenGL程序。这是我的应用程序屏幕：

enter image description here

现在，我的目标是使用OpenCV将我的opengl框架和我的网络摄像头中的框架混合在一个独特的框架中。在使用GLSL着色器之前，我尝试制作一个非常简单的程序，绘制一个带有一些基本OpenGL函数的彩色三角形（glBengin，glVertex等）。

static int      initGL()
{
    if (!glfwInit())
        return (-1);

    if (!glfwOpenWindow(500, 500, 8, 8, 8, 0, 24, 0, GLFW_WINDOW)) {
        glfwTerminate();
        return (-1);
    }

    glEnable(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45.0f, 500.0f / 500.0f, 0.1f, 100.0f);
    gluLookAt(0.0f, 0.0f, 5.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f);

    return (0);
}

static void     drawGL()
{
    glBegin(GL_TRIANGLES);
    glColor3ub(255, 0, 0);
    glVertex3f(-1.0f, 0.0f, 0.0f);
    glColor3ub(0, 255, 0);
    glVertex3f(0.0f, 1.0f, 0.0f);
    glColor3ub(0, 0, 255);
    glVertex3f(1.0f, 0.0f, 0.0f);
    glEnd();
}

int             main(void)
{
    initGL();

    CvCapture   *capture = cvCaptureFromCAM(CV_CAP_ANY);

    if (!capture) {
        fprintf(stderr, "ERROR: capture is NULL \n");
        getchar();
        return (-1);
    }

    while (1)
    {
        glClear(GL_COLOR_BUFFER_BIT);
        glEnable(GL_MODELVIEW);

        IplImage    *frame = cvQueryFrame(capture);

        if (!frame) {
            fprintf(stderr, "ERROR: frame is null...\n");
            getchar();
            break;
        }

        glDrawPixels(frame->width, frame->height, GL_RGB, GL_UNSIGNED_BYTE, frame->imageData);

        drawGL();

        glfwSwapBuffers();

        if ( (cvWaitKey(10) & 255) == 27 ) break;
    }

    cvReleaseCapture(&capture);
    cvDestroyWindow("mywindow");

    return (EXIT_SUCCESS);
}

这是渲染：

enter image description here

如您所见，结果是正确的。现在，我想尝试使用带有OpenCV的GLSL着色器的第一个程序，如下所示，但是当我的应用程序启动时，我有一个黑屏。我尝试了几个测试，当我调用glUseProgram函数时，问题似乎就开始了（所以当我想绑定程序着色器 - ＆gt;在我的代码中它对应于program-＆gt; bind（）调用）。但在这里我使用glDrawPixels函数来加载我的视频帧。如果我想使用GLSL着色器，我认为调用它不是很好的功能。这是我的C ++代码：

[...]

/*My GLSL shaders initialization*/

[...]
int                         main(int ac, char **av)
{
    bool                    isAlive = true;
    unsigned int            vaoID = 0;
    SDL_Event               event;
    GLuint                  textureID = 0;
    ShaderProgram           *program = NULL;

    if (!glfwInit())
        return (-1);

    if (!glfwOpenWindow(WIDTH, HEIGHT, 8, 8, 8, 0, 24, 0, GLFW_WINDOW)) {
        glfwTerminate();
        return (-1);
    }

    glEnable(GL_DEPTH_TEST);

    //Viewport initialization

    glViewport(0, 0, WIDTH, HEIGHT);

    //Vertex declaration

    VertexDeclaration *vDeclar = initVertexDeclaration();

    //Glew init component

    glewInit();

    //VBO initialization

    VertexBuffer *vBuffer = initVBO();

    //Shaders initialization

    program = initShaders("triangle-pf.vert", "triangle-pf.frag");

    //Texture initialization

    textureID = loadBMPTexture("Box.bmp");

    //VAO initialization

    initVAO(vaoID, vBuffer, textureID, vDeclar);

    //Screen capture Initialization

    CvCapture   *capture = cvCaptureFromCAM(CV_CAP_ANY);

    if (!capture) {
        fprintf(stderr, "ERROR: capture is NULL \n");
        getchar();
        return (-1);
    }

    //Main loop

    while (isAlive == true)
    {
        //eventListener(&event, &isAlive);

        if (glfwGetKey(GLFW_KEY_ESC))
            isAlive = false;

        glClearDepth(1.0f);
        glClearColor(0.13f, 0.12f, 0.13f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        //---------------------------------------------------

        IplImage    *frame = cvQueryFrame(capture);

        if (!frame) {
            fprintf(stderr, "ERROR: frame is null...\n");
            getchar();
            break;
        }

        //---------------------------------------------------

        program->bind();

        //Projection matrix

        glm::mat4 ProjectionMatrix = glm::perspective(45.0f, 500.0f / 500.0f, 0.1f, 100.0f);

        //View matrix

        glm::mat4 ViewMatrix = glm::lookAt(glm::vec3(0.0f, 0.0f, 8.0f), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));

        //Model matrix

        glm::mat4 ModelMatrix = glm::mat4(1.0f);
        ModelMatrix = glm::translate(ModelMatrix, glm::vec3(0.0f, 0.0f, 0.0f));
        ModelMatrix = glm::rotate(ModelMatrix, angle, glm::vec3(1.0f, 1.0f, 1.0f));
        ModelMatrix = glm::scale(ModelMatrix, glm::vec3(1.0f, 1.0f, 1.0f));

        //Prepare matrix

        glm::mat4 ModelViewMatrix = ViewMatrix * ModelMatrix;
        glm::mat3 NormalMatrix = glm::mat3(glm::vec3(ModelViewMatrix[0]), glm::vec3(ModelViewMatrix[1]), glm::vec3(ModelViewMatrix[2]));
        glm::mat4 ModelViewProjectionMatrix = ProjectionMatrix * ModelViewMatrix;
        glm::vec4 LightPositionVec1 = ViewMatrix * glm::vec4(LightPosition1[0], LightPosition1[1], LightPosition1[2], LightPosition1[3]);

        //Send source light properties

        program->setUniform("LightInfos[0].La", glm::vec3(0.000000f, 0.000000f, 0.000000f));
        program->setUniform("LightInfos[0].Ld", glm::vec3(0.800000f, 0.800000f, 0.800000f));
        program->setUniform("LightInfos[0].Ls", glm::vec3(1.000000f, 1.000000f, 1.000000f));
        program->setUniform("LightInfos[0].Le", glm::vec3(0.200000f, 0.200000f, 0.200000f));

        /*program->setUniform("LightInfos[1].La", glm::vec3(0.000000f, 0.000000f, 0.000000f));
        program->setUniform("LightInfos[1].Ld", glm::vec3(0.800000f, 0.800000f, 0.800000f));
        program->setUniform("LightInfos[1].Ls", glm::vec3(0.000000f, 1.000000f, 1.000000f));
        program->setUniform("LightInfos[1].Le", glm::vec3(0.200000f, 0.200000f, 0.200000f));*/

        //Send model materials properties

        program->setUniform("MaterialInfos.Ka", glm::vec3(0.000000f, 0.000000f, 0.000000f));
        program->setUniform("MaterialInfos.Kd", glm::vec3(1.000000f, 1.000000f, 1.000000f));
        program->setUniform("MaterialInfos.Ks", glm::vec3(1.000000f, 1.000000f, 1.000000f));
        program->setUniform("MaterialInfos.Ke", glm::vec3(0.200000f, 0.000000f, 0.200000f));
        program->setUniform("MaterialInfos.Shininess", 10.0f);

        //Send light position

        program->setUniform("LightInfos[0].Position", LightPositionVec1);

        //Send matrix

        program->setUniform("ProjectionMatrix", ProjectionMatrix);
        program->setUniform("NormalMatrix", NormalMatrix);
        program->setUniform("ModelViewMatrix", ModelViewMatrix);
        program->setUniform("ModelMatrix", ModelMatrix);
        program->setUniform("MVP", ModelViewProjectionMatrix);

        glDrawPixels(frame->width, frame->height, GL_RGB, GL_UNSIGNED_BYTE, frame->imageData);

        //VAO binding

        glBindVertexArray(vaoID);

        //Render meshes

        glDrawArrays(GL_TRIANGLES, 0, vBuffer->getSize());

        glBindVertexArray(0);

        program->release();

        angle += 0.50f;

        glFlush();
        glfwSwapBuffers();
    }

    unsigned int vboID = vBuffer->getHandle();
    glDeleteBuffers(1, &vboID);
    glDeleteVertexArrays(1, &vaoID);
    return (0);
}

所以我认为问题来自glDrawPixels，它不能与GLSL着色器一起使用。我尝试了几种可能的方法但没有成功。也许我必须将视频帧缓冲区直接发送到像素着色器？在这种情况下，我该怎么做？我真的迷路了。有人可以帮助我吗？

Answer 1

您设置它的方法是将图像数据用作纹理。 This link可能是一个很好的起点。然后，您可以在背景中渲染四边形，填充整个屏幕，并使用纹理来确定每个像素的颜色。优于glDrawPixels()的优点是，如果缩放窗口（和四边形），视频中的图像将相应缩放。

如果需要，可以在渲染四边形时在着色器中使用纹理：为每个像素调用片段（像素）着色器，然后使用采样器从纹理中获取颜色。然后，您可以根据照明需要修改该颜色。

你在此基础上绘制的内容取决于你。

使用GLSL着色器的OpenCV OpenGL渲染无法正常工作

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