//LogSample.fs 用于对原始图像进行采样，并对计算采样后像素的亮度，然后再对亮度取对数后输出。

#version 120
#extension GL_ARB_draw_buffers : enable

uniform sampler2D texSrc;

void main()
{
    vec4 lumfact = vec4(0.27,0.67,0.06,0.0);
    vec4 color = texture2D(texSrc,gl_TexCoord[0].xy);
    float lum = log(dot(color , lumfact) + 0.0001);
    gl_FragData[0] = vec4(lum,lum,lum,1.0);

}