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使用方法:
auto spr = Sprite::create("spr.png");
auto program = CCGLProgram::createWithFilenames("gray.vsh", "gray.fsh"); //装配一个shader文件
program->link();
program->updateUniforms();
spr->setShaderProgram(program);
this->addChild(spr);
gray.vsh:
attribute vec4 a_position; //内置的默认坐标
attribute vec2 a_texCoord; //内置的默认纹理坐标
attribute vec4 a_color; //内置的默认颜色
varying vec4 v_fragmentColor;
varying vec2 v_texCoord;
void main()
{
gl_Position = CC_PMatrix * a_position;
v_fragmentColor = a_color;
v_texCoord = a_texCoord;
}
gray.fsh:
varying vec4 v_fragmentColor;
varying vec2 v_texCoord;
void main(void)
{
vec4 c = texture2D(CC_Texture0, v_texCoord);
gl_FragColor.xyz = vec3(0.2126*c.r + 0.7152*c.g + 0.0722*c.b);
gl_FragColor.w = c.w;
}
原理比较简单,gl_FragColor是shader的内建变量,表示当前片段的颜色,代码中是把从采样器中(CC_Texture0)拿到的颜色值进行一个变灰处理后,最后得到的颜色值再赋值给gl_FragColor