Question

我正在尝试在OpenGL中创建一个场景来模拟太空中的地球。我现在有两个球体，一个用于地球，另一个用于云层。地球和云球体对象有自己的着色器程序，以保持简单。地球着色器程序采用4种纹理（白天，夜晚，specmap和法线贴图），云着色器程序采用2种纹理（cloudmap和normalmap）。我有一个具有渲染功能的对象类，在该函数中我使用这个逻辑：

//bind the current object's texture
for (GLuint i = 0; i < texIDs.size(); i++){
    glActiveTexture(GL_TEXTURE0 + i);
    if (cubemap)
        glBindTexture(GL_TEXTURE_CUBE_MAP, texIDs[i]);
    else
        glBindTexture(GL_TEXTURE_2D, texIDs[i]);
}
    if (samplers.size()){
    for (GLuint i = 0; i < samplers.size(); i++){
        glUniform1i(glGetUniformLocation(program, samplers[i]), i);
    }
}

它从第0个纹理单元开始，并将N个纹理绑定到从GL_TEXTURE0开始的N个纹理单元。然后它在着色器程序中将采样器从0开始绑定到N.加载纹理时，我提供了采样器：

void Object::loadTexture(const char* filename, const GLchar* sampler){
    int texID;
    texID = SOIL_load_OGL_texture(filename, SOIL_LOAD_AUTO, SOIL_CREATE_NEW_ID, SOIL_FLAG_MIPMAPS | SOIL_FLAG_TEXTURE_REPEATS);
    if(texID == 0){
        cerr << "SOIL error: " << SOIL_last_result();
    }
    cout << filename << " Tex ID: " << texID << endl;
    texIDs.push_back(texID);
    samplers.push_back(sampler);
    //glBindTexture(GL_TEXTURE_2D, texID);
}

当我这样做时，第一个球体（地球）中的所有纹理都成功加载，但是在秒球体中我没有纹理，我得到一个黑色球体。我的问题是，如果我为每个对象使用不同的着色器程序，我该如何管理多个纹理和采样器呢？

Answer 1

从我看到你将所有纹理绑定为单独的纹理单元

这是错误的
如果你有100个物体，每个物体有4个纹理......
我强烈怀疑你有400个纹理单位
纹理ID（名称）不是纹理单元...

我像这样渲染太空物体：

First pass renders the astro body geometry
- 我有特定任务的特定纹理单元
```
// texture units:            
// 0 - texture0 map 2D rgba (surface)
// 1 - texture1 map 2D rgba (clouds blend)
// 2 - normal map 2D xyz (normal/bump mapping)
// 3 - specular map 2D i (reflection shininess)
// 4 - light map 2D rgb rgb (night lights)
// 5 - enviroment/skybox cube map 3D rgb
```
- 查看该链接中的着色器（它也是为太阳系可视化而编写的）...
- 在每次渲染之前，只绑定单个纹理的纹理
- （绑定着色器后）
- 不要改变纹理单位的含义（如果你这样做，着色器将如何知道哪种纹理？）
Second render pass adds atmospheres
- 没有使用纹理
- 它只是单个透明四边形覆盖整个屏幕
here some insights to your tasks

[edit1]多纹理的例子

// init shader once per render all geometries
GLint prog_id;      // shader program ID;
GLint txrskybox;    // global skybox environment cube map
GLint id;
glUseProgram(prog_id);
id=glGetUniformLocation(prog_id,"txr_texture0"); glUniform1i(id,0); //uniform sampler2D   txr_texture0;
id=glGetUniformLocation(prog_id,"txr_texture1"); glUniform1i(id,1); //uniform sampler2D   txr_texture1;
id=glGetUniformLocation(prog_id,"txr_normal");   glUniform1i(id,2); //uniform sampler2D   txr_normal;
id=glGetUniformLocation(prog_id,"txr_specular"); glUniform1i(id,3); //uniform sampler2D   txr_specular;
id=glGetUniformLocation(prog_id,"txr_light");    glUniform1i(id,4); //uniform sampler2D   txr_light;
id=glGetUniformLocation(prog_id,"txr_skybox");   glUniform1i(id,5); //uniform samplerCube txr_skybox;

// add here all uniforms you need ...
glActiveTexture(GL_TEXTURE0+5); glEnable(GL_TEXTURE_CUBE_MAP); glBindTexture(GL_TEXTURE_CUBE_MAP,txrskybox);

for (i=0;i<all_objects;i++)
    {
    // add here all uniforms you need ...

    // pass textures once per any object render
    // obj::(GLint) txr0,txr1,txrnor,txrspec,txrlight; // object local textures
    glActiveTexture(GL_TEXTURE0+0); glEnable(GL_TEXTURE_2D); glBindTexture(GL_TEXTURE_2D,obj[i].txr0);
    glActiveTexture(GL_TEXTURE0+1); glEnable(GL_TEXTURE_2D); glBindTexture(GL_TEXTURE_2D,obj[i].txr1);
    glActiveTexture(GL_TEXTURE0+2); glEnable(GL_TEXTURE_2D); glBindTexture(GL_TEXTURE_2D,obj[i].txrnor);
    glActiveTexture(GL_TEXTURE0+3); glEnable(GL_TEXTURE_2D); glBindTexture(GL_TEXTURE_2D,obj[i].txrspec);
    glActiveTexture(GL_TEXTURE0+4); glEnable(GL_TEXTURE_2D); glBindTexture(GL_TEXTURE_2D,obj[i].txrlight);
    // here render the geometry of obj[i]
    }

// unbind textures and shaders
glActiveTexture(GL_TEXTURE0+5); glBindTexture(GL_TEXTURE_CUBE_MAP,0); glDisable(GL_TEXTURE_CUBE_MAP);
glActiveTexture(GL_TEXTURE0+4); glBindTexture(GL_TEXTURE_2D,0); glDisable(GL_TEXTURE_2D);
glActiveTexture(GL_TEXTURE0+3); glBindTexture(GL_TEXTURE_2D,0); glDisable(GL_TEXTURE_2D);
glActiveTexture(GL_TEXTURE0+2); glBindTexture(GL_TEXTURE_2D,0); glDisable(GL_TEXTURE_2D);
glActiveTexture(GL_TEXTURE0+1); glBindTexture(GL_TEXTURE_2D,0); glDisable(GL_TEXTURE_2D);
glActiveTexture(GL_TEXTURE0+0); glBindTexture(GL_TEXTURE_2D,0); glDisable(GL_TEXTURE_2D); // unit0 at last so it stays active ...
glUseProgram(0);

具有多个着色器程序的OpenGL多重纹理

1 个答案: