OpenGL（GLSL）未写入正确的帧缓冲区纹理

Question

我有一个附加了两个纹理的帧缓冲区，读取调用：

Occlusion = texture2D(OcclusionTexture, TexCoord);
FragColor = texture2D(ColourTexture, TexCoord);

返回相同的东西。它们返回驻留在纹理OcclusionTexture 中的数据。任何帮助请，对不起代码墙。

着色器代码： 附件

 subroutine void RenderPassType();
    subroutine uniform RenderPassType RenderPass;

    uniform sampler2D ColourTexture;
    uniform sampler2D OcclusionTexture;
    layout(location = 0) out vec4 FragColor; // Actual fragment colour;
    layout(location = 1) out vec3 OutColour;
    layout(location = 2) out vec3 OcclusionColour;

写作和阅读

    subroutine (RenderPassType) void Write()
    {
        // Writing
        OcclusionColour = vec3(m_Light[0].Intensity);
        OutColour = vec3(ApplyFog(ViewPos, Colour, fogColour,                   fogDistance)); 
    } 

    subroutine (RenderPassType) void Read()
    {
        // Reading
        vec4 Occlusion = texture2D(OcclusionTexture, TexCoord);
        FragColor = texture2D(ColourTexture, TexCoord);
    }

生成帧缓冲区和纹理的代码：

// Create and bind the FBO
glGenFramebuffers(1, &FBO);
glBindFramebuffer(GL_FRAMEBUFFER, FBO);

// The depth buffer
glGenRenderbuffers(1, &DepthBuff);
glBindRenderbuffer(GL_RENDERBUFFER, DepthBuff);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, 
    settings::GameSettings::GetSingleton()->Screen.x, settings::GameSettings::GetSingleton()->Screen.y);

// The color buffer
glActiveTexture(GL_TEXTURE0);
glGenTextures(1, &ScreenTex);
glBindTexture(GL_TEXTURE_2D, ScreenTex);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, settings::GameSettings::GetSingleton()->Screen.x
    , settings::GameSettings::GetSingleton()->Screen.y, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

// The occlusion buffer
glActiveTexture(GL_TEXTURE1);
glGenTextures(1, &OcclusionTex);
glBindTexture(GL_TEXTURE_2D, OcclusionTex);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, settings::GameSettings::GetSingleton()->Screen.x
    , settings::GameSettings::GetSingleton()->Screen.y, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

// Attach the images to the framebuffer
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, DepthBuff);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, ScreenTex, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, OcclusionTex, 0);

GLenum drawBuffers[] = { GL_NONE, GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1};

glDrawBuffers(3, drawBuffers);
glBindFramebuffer(GL_FRAMEBUFFER, 0);

SetUniform("ColourTexture", ScreenTex);
SetUniform("OcclusionTexture", OcclusionTex);

/////////////////////////////////////// /////// 编辑 ///////////////////////////////////////// ////

第一遍我将场景渲染到纹理。在第二遍中，我只读取纹理并进行体积光照计算，然后将最终的碎片颜色推送到附件 0。

Answer 1

你的纹理绑定是错误的。它应该看起来像这样：

SetUniform("ColourTexture", 0);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, ScreenTex);

SetUniform("OcclusionTexture", 1);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, OcclusionTex);
//draw stuff

注意：重要的部分在这里，活动纹理单元的编号被传递给制服而不是纹理ID。

Answer 2

纹理的问题在于我正在绑定和取消绑定着色器程序。

glUseProgram(m_shaderProgramHandle); //bind program
glUseProgram(0); //unbind a program

纹理仅在着色器启动时绑定到它们的纹理单元，因为着色器被解除绑定，它也解除了纹理单元的绑定。解决方法是：

void StandardLightingShader::Begin() 
{
    glUseProgram(m_shaderProgramHandle);

    // Set up Pass
    glBindFramebuffer(GL_FRAMEBUFFER, FBO);
    glEnable(GL_DEPTH_TEST);
    glUniformSubroutinesuiv(GL_FRAGMENT_SHADER, 1, &pass1Index);
    SetUniform("ScreenSize", settings::GameSettings::GetSingleton()->Screen);
    SetUniform("ScreenOffSet", settings::GameSettings::GetSingleton()->ScreenPosition);

    // Bind the textures to texture units.
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, ScreenTex);

    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, OcclusionTex);

}

因此，基本上，如果您取消绑定程序，则需要将纹理重新绑定到纹理单元，但实际的统一变量将通过着色器更改持续存在。

SetUniform("ColourTexture", 0);