OpenGL：使用多个纹理渲染到 FBO

Posted 2023-02-22

【中文标题】OpenGL：使用多个纹理渲染到 FBO

【英文标题】：OpenGL: Render to FBO using multiple textures

【发布时间】：2010-10-10 22:27:08

【问题描述】：

我正在尝试使用渲染器。我想要的是将一个颜色缓冲区和一个普通缓冲区写入两个单独的纹理。我弄明白了那部分。

但是，颜色缓冲区应该是两个纹理的组合。这应该可以解决问题：

glActiveTexture(GL_TEXTURE0_ARB);
glEnable(GL_TEXTURE_2D);
g_Tex->Bind();

glActiveTexture(GL_TEXTURE1_ARB);
glEnable(GL_TEXTURE_2D);
g_TexNormal->Bind();

    g_Shader->Enable();
        RenderScene();
    g_Shader->Disable();

glActiveTexture(GL_TEXTURE1_ARB);
glDisable(GL_TEXTURE_2D);

glActiveTexture(GL_TEXTURE0_ARB);
glDisable(GL_TEXTURE_2D);

这是片段着色器：(GLSL)

uniform sampler2D tex_diffuse;
uniform sampler2D tex_normal;

void main()

    gl_FragColor = texture2D(tex_diffuse, gl_TexCoord[0].st);
    //gl_FragColor = texture2D(tex_normal, gl_TexCoord[0].st);
   

但是，第二个纹理与第一个相同！附加到GL_TEXTURE0 的任何纹理都是用于两个采样器的纹理。

初始化 FBO：

glGenFramebuffersEXT(1, &g_FBOColor);
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, g_FBOColor);

glGenTextures(1, &g_FBOTexColor);
glBindTexture(GL_TEXTURE_2D, g_FBOTexColor);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
glBindTexture(GL_TEXTURE_2D, 0);
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, g_FBOTexColor, 0);

glGenTextures(1, &g_FBOTexNormal);
glBindTexture(GL_TEXTURE_2D, g_FBOTexNormal);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
glBindTexture(GL_TEXTURE_2D, 0);
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT1_EXT, GL_TEXTURE_2D, g_FBOTexNormal, 0);

glGenTextures(1, &g_FBOTexDepth);
glBindTexture(GL_TEXTURE_2D, g_FBOTexDepth);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT24, w, h, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, NULL);
glBindTexture(GL_TEXTURE_2D, 0);
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_TEXTURE_2D, g_FBOTexDepth, 0);

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

完整的渲染部分：

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, g_FBOColor);
glPushAttrib(GL_VIEWPORT_BIT | GL_COLOR_BUFFER_BIT);

glViewport(
    0, 0,
    Window::GetSingleton()->GetWidth(), Window::GetSingleton()->GetHeight()
);

GLenum buffers[] =  GL_COLOR_ATTACHMENT0_EXT, GL_COLOR_ATTACHMENT1_EXT ;
glDrawBuffers(2, buffers);
//glReadBuffer(GL_COLOR_ATTACHMENT0_EXT | GL_COLOR_ATTACHMENT1_EXT);

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glActiveTexture(GL_TEXTURE0_ARB);
glEnable(GL_TEXTURE_2D);
g_Tex->Bind();

glActiveTexture(GL_TEXTURE1_ARB);
glEnable(GL_TEXTURE_2D);
g_TexNormal->Bind();

    g_Shader->Enable();
        RenderScene();
    g_Shader->Disable();

glActiveTexture(GL_TEXTURE1_ARB);
glDisable(GL_TEXTURE_2D);

glActiveTexture(GL_TEXTURE0_ARB);
glDisable(GL_TEXTURE_2D);

glPopAttrib();
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

提前致谢。

【问题讨论】：

请注意，当绑定它们以进行渲染时，不应调用 glActiveTexture 或 glEnable(GL_TEXTURE_2D)。只有在实际渲染应该显示这些纹理的几何体时才应该使用它们（即渲染到纹理的结果）。

【参考方案1】：

嗯，我想通了。 :)

我的纹理不起作用的原因是我没有设置统一的位置。固定代码：

g_Shader->Enable();

    glActiveTexture(GL_TEXTURE0_ARB);
    glEnable(GL_TEXTURE_2D);
    g_Tex->Bind();
    glUniform1i(glGetUniformLocation(g_Shader->GetProgram(), "tex_diffuse"), 0);

    glActiveTexture(GL_TEXTURE1_ARB);
    glEnable(GL_TEXTURE_2D);
    g_TexNormal->Bind();
    glUniform1i(glGetUniformLocation(g_Shader->GetProgram(), "tex_normal"), 1);

        RenderScene();

    glActiveTexture(GL_TEXTURE1_ARB);
    glDisable(GL_TEXTURE_2D);

    glActiveTexture(GL_TEXTURE0_ARB);
    glDisable(GL_TEXTURE_2D);

g_Shader->Disable();