2 个纹理，1 个着色器 - OpenGL ES 2.0

Question

这里是 ES 2.0 新手。我目前正在尝试使用 ES 2.0 和 PowerVR SDK 从立体图像制作一些 3D 隔行扫描图像。我可以很好地输出一个图像纹理，但是当我尝试输出第二个时，我似乎覆盖了第一个。所以，我的问题是，给定下面的片段着色器，我可以用它来绘制两个纹理，还是 sampler2d 制服只能绑定到一个纹理单元？ 这是片段着色器（取自 PowerVR“培训课程”示例程序）：

    uniform sampler2D sampler2d;\
    varying mediump vec2    myTexCoord;\
    void main (void)\
    {\
        gl_FragColor = texture2D(sampler2d,myTexCoord);\
    }";

下面是我如何将图像纹理加载到着色器中：

//LEFT IMAGE
glActiveTexture(GL_TEXTURE0);
glGenTextures(1, &m_uiTexture_left);                                    
glBindTexture(GL_TEXTURE_2D, m_uiTexture_left);
glUniform1i(glGetUniformLocation(m_uiProgramObject, "sampler2d"), 0);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, pwr2Width, pwr2Height,0, GL_RGB, GL_UNSIGNED_BYTE, xImageL); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
GLfloat afVertices[30] = {0.0};
genVertices(afVertices);
glGenBuffers(1, &m_ui32Vbo_leftimage);                                  
m_ui32VertexStride = 5 * sizeof(GLfloat); // 3 floats for the pos, 2 for the UVs
glBindBuffer(GL_ARRAY_BUFFER, m_ui32Vbo_leftimage);
glBufferData(GL_ARRAY_BUFFER, 6 * m_ui32VertexStride, afVertices, GL_STATIC_DRAW);  
glBindBuffer(GL_ARRAY_BUFFER, 0);

//RIGHT IMAGE
glActiveTexture(GL_TEXTURE1);
glGenTextures(1, &m_uiTexture_right);                                   
glBindTexture(GL_TEXTURE_2D, m_uiTexture_right);
glUniform1i(glGetUniformLocation(m_uiProgramObject, "sampler2d"), 1);   
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, pwr2Width, pwr2Height,0, GL_RGB, GL_UNSIGNED_BYTE, xImageR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glGenBuffers(1, &m_ui32Vbo_rightimage);                     
m_ui32VertexStride = 5 * sizeof(GLfloat); // 3 floats for the pos, 2 for the UVs
glBindBuffer(GL_ARRAY_BUFFER, m_ui32Vbo_rightimage);
glBufferData(GL_ARRAY_BUFFER, 6 * m_ui32VertexStride, afVertices, GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);

那么，这段代码是否只是覆盖了 sampler2d 制服？第二张图像是否需要另一个制服或着色器？

Answer 1

好的，正如我在上面的评论中提到的，我最终在这里找到了答案：http://www.opentk.com/node/2559。正如该论坛上的用户“Profet”所提到的，重用片段着色器的一种方法是将 glUniform1i() 调用向下移动到渲染函数，即调用 glUniform1i() 将第一个纹理传递给着色器，调用glDraw（绘制纹理），然后调用 glUniform1i() 并将第二个纹理传递给着色器（并绘制）。所以现在我的initialise()代码如下：

//LEFT IMAGE
glActiveTexture(GL_TEXTURE0);
glGenTextures(1, &m_uiTexture_left);                                    
glBindTexture(GL_TEXTURE_2D, m_uiTexture_left);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, pwr2Width, pwr2Height,0, GL_RGB, GL_UNSIGNED_BYTE, xImageL); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
GLfloat afVertices[30] = {0.0};
genVertices(afVertices);
glGenBuffers(1, &m_ui32Vbo_leftimage);                                  
m_ui32VertexStride = 5 * sizeof(GLfloat); // 3 floats for the pos, 2 for the UVs
glBindBuffer(GL_ARRAY_BUFFER, m_ui32Vbo_leftimage);
glBufferData(GL_ARRAY_BUFFER, 6 * m_ui32VertexStride, afVertices, GL_STATIC_DRAW);  
glBindBuffer(GL_ARRAY_BUFFER, 0);

//RIGHT IMAGE
glActiveTexture(GL_TEXTURE1);
glGenTextures(1, &m_uiTexture_right);                                   
glBindTexture(GL_TEXTURE_2D, m_uiTexture_right);   
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, pwr2Width, pwr2Height,0, GL_RGB, GL_UNSIGNED_BYTE, xImageR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glGenBuffers(1, &m_ui32Vbo_rightimage);                     
m_ui32VertexStride = 5 * sizeof(GLfloat); // 3 floats for the pos, 2 for the UVs
glBindBuffer(GL_ARRAY_BUFFER, m_ui32Vbo_rightimage);
glBufferData(GL_ARRAY_BUFFER, 6 * m_ui32VertexStride, afVertices, GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);

我的 render() 代码如下：

//&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&  LEFT IMAGE &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
glEnable(GL_STENCIL_TEST);
glStencilFunc(GL_NOTEQUAL, 1, 1); //draw on uneven lines only
glUniform1i(glGetUniformLocation(m_uiProgramObject, "sampler2d"), 0); //pass texture unit 0 to shader
glBindBuffer(GL_ARRAY_BUFFER, m_ui32Vbo_leftimage);     // unbound this near the end of initView, so need to re-bind it
glEnableVertexAttribArray(VERTEX_ARRAY);
glVertexAttribPointer(VERTEX_ARRAY, 3, GL_FLOAT, GL_FALSE, m_ui32VertexStride, 0);
glEnableVertexAttribArray(TEXCOORD_ARRAY);
glVertexAttribPointer(TEXCOORD_ARRAY, 2, GL_FLOAT, GL_FALSE, m_ui32VertexStride, (void*) (3 * sizeof(GLfloat)));
glDrawArrays(GL_TRIANGLES, 0, 6);
glBindBuffer(GL_ARRAY_BUFFER, 0);
//&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&  RIGHT IMAGE  &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
glEnable(GL_STENCIL_TEST);
glStencilFunc(GL_EQUAL, 1, 1);  //draw on even lines only
glUniform1i(glGetUniformLocation(m_uiProgramObject, "sampler2d"), 1);
glBindBuffer(GL_ARRAY_BUFFER, m_ui32Vbo_rightimage);
glEnableVertexAttribArray(VERTEX_ARRAY);
glVertexAttribPointer(VERTEX_ARRAY, 3, GL_FLOAT, GL_FALSE, m_ui32VertexStride, 0);
glEnableVertexAttribArray(TEXCOORD_ARRAY);
glVertexAttribPointer(TEXCOORD_ARRAY, 2, GL_FLOAT, GL_FALSE, m_ui32VertexStride, (void*) (3 * sizeof(GLfloat)));
glDrawArrays(GL_TRIANGLES, 0, 6);
glBindBuffer(GL_ARRAY_BUFFER, 0);

希望有一天这对某人有所帮助！ :)

Answer 2

正确的方法是将你想要的纹理发送到你想要的纹理单元： http://www.opengl.org/wiki/Sampler_(GLSL)#Binding_textures_to_samplers