Question

我正在进行一个项目，我需要从SPH粒子模拟水中获取表面，以便以卡通风格呈现它。为了做到这一点，我遵循一个方法，第一步是从这个粒子集中获取深度图，我试图在帧缓冲区对象中渲染离屏，并渲染在屏幕上作为测试，看到结果。现在我还没有呈现任何粒子，因为我首先尝试在这个FBO上渲染一些东西并在四边形上渲染它，遵循Swiftless网站的教程。当然，我已经将那里解释的方法添加到了我正在进行的项目中。

我的第一步是渲染一个带有灰色茶壶的绿色屏幕，工作没有问题，你可以看到here。

然后我尝试将它渲染到一个FBO屏幕上，然后将它渲染到屏幕中间的四边形，但我得到的只是一个绿色四边形，你可以看到here。 / p>

我使用的代码直接来自我之前提到过的教程，是这样的：

变量：

GLuint fbo;
GLuint fbo_depth;
GLuint fbo_texture;

int windowWidth  = 1024;
int windowHeight = 768;

设置FBO及其纹理：

void initFrameBufferDepthBuffer () 
{
    glGenRenderbuffersEXT(1, &fbo_depth); // Generate one render buffer and store the ID in fbo_depth
    glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, fbo_depth); // Bind the fbo_depth render buffer  
    glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT, windowWidth, windowHeight); // Set the render buffer storage to be a depth component, with a width and height of the window  

    glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, fbo_depth); // Set the render buffer of this buffer to the depth buffer  
    glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, 0); // Unbind the render buffer 
}

void initFrameBufferTexture () 
{  
    glGenTextures(1, &fbo_texture); // Generate one texture  

    glBindTexture(GL_TEXTURE_2D, fbo_texture); // Bind the texture fbo_texture  

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, windowWidth, windowHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); // Create a standard texture with the width and height of our window  

    // Setup the basic texture parameters  
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);  
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);  
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);  
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);  

    // Unbind the texture  
    glBindTexture(GL_TEXTURE_2D, 0);  
}

void initFrameBuffer () {  
    glEnable(GL_TEXTURE_2D); // Enable texturing so we can bind our frame buffer texture  
    glEnable(GL_DEPTH_TEST); // Enable depth testing

    initFrameBufferDepthBuffer(); // Initialize our frame buffer depth buffer  
    initFrameBufferTexture(); // Initialize our frame buffer texture  

    glGenFramebuffersEXT(1, &fbo); // Generate one frame buffer and store the ID in fbo  
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo); // Bind our frame buffer  
    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, fbo_texture, 0); // Attach the texture fbo_texture to the color buffer in our frame buffer
    glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, fbo_depth); // Attach the depth buffer fbo_depth to our frame buffer

    GLenum status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT); // Check that status of our generated frame buffer  

    if (status != GL_FRAMEBUFFER_COMPLETE_EXT) // If the frame buffer does not report back as complete  
    {  
        printf ( "Couldn't create frame buffer\n");
    }  

    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0); // Unbind our frame buffer  

    glDisable(GL_TEXTURE_2D);
    glDisable(GL_DEPTH_TEST);
}

在FBO上渲染茶壶：

void renderTeapotScene () 
{  
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo); // Bind our frame buffer for rendering  
    glPushAttrib(GL_VIEWPORT_BIT | GL_ENABLE_BIT); // Push our glEnable and glViewport states  
    glViewport(0, 0, windowWidth, windowHeight); // Set the size of the frame buffer view port  

    glClearColor (0.0f, 1.0f, 0.0f, 1.0f); // Set the clear colour  
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear the depth and colour buffers  

    glLoadIdentity();  // Reset the modelview matrix  

    glTranslatef(0.0f, 0.0f, -5.0f); // Translate back 5 units  

    glColor4f(0.5f, 0.5f, 0.5f, 1.0f);
    glutSolidTeapot(1.0f); // Render a teapot  

    glPopAttrib(); // Restore our glEnable and glViewport states  
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0); // Unbind our texture  
}

在应用程序开始时仅发生一次的进程上设置FBO：

initFrameBuffer(); // Create our frame buffer object

整个过程，每一帧都会发生：

glEnable(GL_TEXTURE_2D); // Enable texturing so we can bind our frame buffer texture  
glEnable(GL_DEPTH_TEST); // Enable depth testing 

renderTeapotScene();

glLoadIdentity(); // Load the Identity Matrix to reset our drawing locations  
glTranslatef(0.0f, 0.0f, -10.0f);  

glBindTexture(GL_TEXTURE_2D, fbo_texture);  

glBegin(GL_QUADS);  
    glTexCoord2f(0.0f, 0.0f);  glVertex3f(-1.0f, -1.0f, 0.0f); // The bottom left corner  
    glTexCoord2f(0.0f, 1.0f);  glVertex3f(-1.0f, 1.0f, 0.0f); // The top left corner  
    glTexCoord2f(1.0f, 1.0f);  glVertex3f(1.0f, 1.0f, 0.0f); // The top right corner  
    glTexCoord2f(1.0f, 0.0f);  glVertex3f(1.0f, -1.0f, 0.0f); // The bottom right corner  
glEnd();  

glBindTexture(GL_TEXTURE_2D, 0);

glDisable(GL_TEXTURE_2D);
glDisable(GL_DEPTH_TEST);

当然，这些代码片段在一个更大的项目中，我认为可能会启用可能导致此行为的内容，但我不知道它可能是什么。我认为重要的是说我的FBO具有与屏幕帧缓冲区相同的宽度和高度。

嗯，这是我现在的情景。有人知道如何将第一张图像渲染到第二张图像中间的四边形作为纹理？

无法将屏幕外帧缓冲区对象的纹理正确渲染为四边形

0 个答案: