帶有多個着色器程序的OpenGL多紋理

Question

我想在OpenGL中做一個場景來模擬來自太空的地球。我現在有兩個球體，一個用於地球，另一個用於雲層。地球和雲球對象有自己的着色器程序來保持簡單。地球着色器程序需要4個紋理（日，夜，specmap和normalmap），雲着色器程序需要2個紋理（雲圖和法線貼圖）。我有具有呈現功能的對象類，並在該功能的我使用這個邏輯：從GL_TEXTURE0開始

//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); 
    } 
} 

它從第0紋理單元開始，並結合紋理的N個以N個紋理單元。然後在着色器程序中將採樣器從0開始綁定到N.採樣器是由我公司提供，同時加載紋理：

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); 
} 

當我做到這一點，在第一球（地球）所有的紋理被加載成功，但在秒球我沒有得到任何紋理和我剛剛得到一個黑色的球體。我的查詢是，如果我爲每個對象使用不同的着色器程序，我應該如何管理多個紋理和採樣器？

Answer 1

從我看到你有約束力的所有紋理作爲獨立的紋理單元

• ，這是錯誤
• 如果你有100個對象，每個人都有4個紋理...
• 我強烈懷疑你有400個紋理單位在您的處置
• 紋理ID（名稱）不是紋理單元...

我使空間機構是這樣的：

1. First pass renders the astro body geometry

   • 我有特殊的紋理單元爲特定任務

     // 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 
     

   • 見日在該路段e着色器（它是太陽系可視化太書面）...

   • 綁定僅在每個前的單機身紋理渲染它
   • （綁定着色器後）
   • 做不會改變紋理單元的含義（如果着色器知道哪個紋理是如何做的話？）

2. Second render pass adds atmospheres

   • 使用
   • 沒有紋理它僅僅是單透明的四覆蓋整個屏幕

3. here some insights to your tasks

[EDIT1]多紋理

// 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);