opengl shader 圖片變灰及還原，使用自己的shader崩潰問題

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本來採用更改圖片像素點變灰，現在需要還原，便用shader，發現變灰和還原後悔改變圖片的位置，於是又尋找解決辦法~

變灰和還原的函數

 

 

void addGray(Sprite* sprite)  
{  
if(sprite)
{
GLProgram * p = new GLProgram();
p->initWithFilenames("gray.vsh", "gray.fsh");
p->bindAttribLocation(GLProgram::ATTRIBUTE_NAME_POSITION, GLProgram::VERTEX_ATTRIB_POSITION);
p->bindAttribLocation(GLProgram::ATTRIBUTE_NAME_COLOR, GLProgram::VERTEX_ATTRIB_COLOR);
p->bindAttribLocation(GLProgram::ATTRIBUTE_NAME_TEX_COORD, GLProgram::VERTEX_ATTRIB_TEX_COORDS);
p->link();
p->updateUniforms();
sprite->setShaderProgram(p);
}
} 

 

 

 

 

 

 

網上down的gray.vsh變灰後改變位置解決辦法：CC_MVPMatrix 改爲CC_PMatrix

 

 

void removeGray(Sprite* sprite)  
{  
CCGLProgram* p = CCShaderCache::sharedShaderCache()->programForKey(GLProgram::SHADER_NAME_POSITION_TEXTURE_COLOR_NO_MVP);
sprite->setShaderProgram(p);
}

 

 

 

 

 

還原本應該設置爲GLProgram::SHADER_NAME_POSITION_TEXTURE_COLOR，但是有會發生位置改變~所以改爲GLProgram::SHADER_NAME_POSITION_TEXTURE_COLOR_NO_MVP

 

使用自己的shader，會崩潰，解決辦法：

 

 

std::string GLProgram::logForOpenGLObject(GLuint object, GLInfoFunction infoFunc, GLLogFunction logFunc) const
{
    std::string ret;
    GLint logLength = 0, charsWritten = 0;


    //infoFunc(object, GL_INFO_LOG_LENGTH, &logLength);        //這裏就崩潰了~~  不知道爲什麼 
    glGetShaderiv(object, GL_INFO_LOG_LENGTH, &logLength);     //直接改成調用opengel函數， 
    if (logLength < 1)
        return "";


    char *logBytes = (char*)malloc(logLength);
    // logFunc(object, logLength, &charsWritten, logBytes); //同上
    glGetShaderInfoLog(object, logLength, &charsWritten, logBytes);
    ret = logBytes;


    free(logBytes);
    return ret;
}

 

 

 

 

 

 

文件：

gray.fsh:

 

varying vec4 v_fragmentColor; 
varying vec2 v_texCoord; 

void main() 
{
vec4 v_orColor = v_fragmentColor * texture2D(CC_Texture0, v_texCoord);
float gray = dot(v_orColor.rgb, vec3(0.299, 0.587, 0.114));
gl_FragColor = vec4(gray, gray, gray, v_orColor.a);
}

gray.vsh:
attribute vec4 a_position;
attribute vec2 a_texCoord;
attribute vec4 a_color;

varying vec4 v_fragmentColor;
varying vec2 v_texCoord;

void main() 
{ 
    gl_Position = CC_PMatrix * a_position;
v_fragmentColor = a_color;
v_texCoord = a_texCoord;
}