标准化设备坐标

标准化设备坐标

坐标

    GLfloat vertex[4*3] =
    {
        -0.5f,  0.5f, 0.0f,     //x,y,z
         0.5f,  0.5f, 0.0f,       
        -0.5f, -0.5f, 0.0f,     
         0.5f, -0.5f, 0.0f,       
    };

坐标

坐标 + 颜色

    GLfloat vertex[ 4* (3+4)] =
    {
        -0.5f,  0.5f, 0.0f,       0.0f, 0.0f, 0.5f, 1.0f, //x,y,z,   r,g,b,a
         0.5f,  0.5f, 0.0f,       0.0f, 0.5f, 0.0f, 1.0f,
        -0.5f, -0.5f, 0.0f,       0.5f, 0.0f, 1.0f, 1.0f,
         0.5f, -0.5f, 0.0f,       0.0f, 0.0f, 0.5f, 1.0f,
    };

坐标 + 颜色

坐标 + 颜色 + 纹理

    GLfloat vertex[ 4* (3+4+2)] =
    {   //x,y,z,                  r,g,b,a                  s,t
        -0.5f,  0.5f, 0.0f,       0.0f, 0.0f, 0.5f, 1.0f,  0.0f, 1.0f,
         0.5f,  0.5f, 0.0f,       0.0f, 0.5f, 0.0f, 1.0f,  1.0f, 0.0f,
        -0.5f, -0.5f, 0.0f,       0.5f, 0.0f, 1.0f, 1.0f,  0.0f, 1.0f,
         0.5f, -0.5f, 0.0f,       0.0f, 0.0f, 0.5f, 1.0f,  1.0f, 1.0f,
    };

坐标 + 颜色 + 纹理

VBO - VAO - EBO(或者叫IBO)

VBO - VAO VBO - VAO - EBO

关于OpenGL ES 的顶点属性配置 :

// Named vertex attributes for mapping GLKEffects logic to client vertex attrib enables
typedef NS_ENUM(GLint, GLKVertexAttrib)
{
    GLKVertexAttribPosition,    //坐标
    GLKVertexAttribNormal,      //这个暂时不知道是什么.
    GLKVertexAttribColor,       //颜色
    GLKVertexAttribTexCoord0,   //纹理0
    GLKVertexAttribTexCoord1    //纹理1
} NS_ENUM_AVAILABLE(10_8, 5_0);

OpenGL ES - GLKBaseEffect中知道

 // 为每个顶点属性创建和初始化VBO
  // 下面的例子显示了一个建立position vertex属性的例子。
  // 对每个附加的所需属性重复以下步骤：normal，color，texCoord0，texCoord1。

  glGenBuffers(1, &positionVBO);
  glBindBuffer(GL_ARRAY_BUFFER, positionVBO);
  glBufferData(GL_ARRAY_BUFFER, vboSize, dataBufPtr, GL_STATIC_DRAW);
  glVertexAttribPointer(GLKVertexAttribPosition, size, type, normalize, stride, NULL);
  glEnableVertexAttribArray(GLKVertexAttribPosition);

  ... 对其他所需的顶点属性重复上述步骤

注意 :

顶点索引的描述顺序 :

• 正面 : 逆时针
• 反面 : 顺时针

在Xcode中开发的话. 形式可以为 :

//顶点数据，前三个是顶点坐标， 中间三个是顶点颜色，    最后两个是纹理坐标
    GLfloat attrArr[] = {
        -0.5f,  0.5f, 0.0f,  0.0f, 0.0f, 1.0f, 1.0f,    0.0f, 1.0f,
         0.5f,  0.5f, 0.0f,  0.0f, 1.0f, 0.0f, 1.0f,    1.0f, 1.0f,
        -0.5f, -0.5f, 0.0f,  1.0f, 0.0f, 1.0f, 1.0f,    0.0f, 0.0f,
         0.5f, -0.5f, 0.0f,  0.0f, 0.0f, 1.0f, 1.0f,    1.0f, 0.0f,
    };
    //顶点索引
    GLuint indices[] = {
        0, 1, 2,
        1, 2, 3,
    };
    
    GLuint buffer;
    glGenBuffers(1, &buffer);
    glBindBuffer(GL_ARRAY_BUFFER, buffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(attrArr), attrArr, GL_STATIC_DRAW);
    
    GLuint index;
    glGenBuffers(1, &index);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
    
    //坐标
    glEnableVertexAttribArray(GLKVertexAttribPosition);
    glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 9, (GLfloat *)NULL);

    //顶点颜色
    glEnableVertexAttribArray(GLKVertexAttribColor);
    glVertexAttribPointer(GLKVertexAttribColor, 4, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 9, (GLfloat *)NULL + 3);
   
    //纹理属性0
    glEnableVertexAttribArray(GLKVertexAttribTexCoord0);
    glVertexAttribPointer(GLKVertexAttribTexCoord0, 2, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 9, (GLfloat *)NULL + 3 + 4);

    //纹理属性1
    glEnableVertexAttribArray(GLKVertexAttribTexCoord1);
    glVertexAttribPointer(GLKVertexAttribTexCoord1, 2, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 9, (GLfloat *)NULL + 3 + 4);
    
    //加载纹理
    NSString* filePath0 = [[NSBundle mainBundle] pathForResource:@"texture0.jpg" ofType:@""];
    NSDictionary* options0 = [NSDictionary dictionaryWithObjectsAndKeys:@(1), GLKTextureLoaderGenerateMipmaps, nil];
    GLKTextureInfo* textureInfo0 = [GLKTextureLoader textureWithContentsOfFile:filePath0 options:options0 error:nil];
    self.mEffect.texture2d0.enabled = GL_TRUE;
    self.mEffect.texture2d0.name = textureInfo0.name;
    
    //加载纹理
    NSString* filePath1 = [[NSBundle mainBundle] pathForResource:@"texture1.png" ofType:@""];
    NSDictionary* options1 = [NSDictionary dictionaryWithObjectsAndKeys:@(1), GLKTextureLoaderOriginBottomLeft, nil];
    GLKTextureInfo* textureInfo1 = [GLKTextureLoader textureWithContentsOfFile:filePath1 options:options1 error:nil];
    self.mEffect.texture2d1.enabled = GL_TRUE;
    self.mEffect.texture2d1.name = textureInfo1.name;

PS : self.mEffect

- (GLKBaseEffect *)mEffect {
    if (_mEffect == nil) {
        _mEffect = [[GLKBaseEffect alloc]init];
    }
    return _mEffect;
}