图片混合变亮与变暗的效果，如下图所示


变暗效果


变亮效果


变亮shader

uniformsampler2DU_MainTexture;uniformsampler2DU_SubTexture;varyingvec2M_coord;voidmain(){vec4blendColor=texture2D(U_SubTexture,M_coord);vec4baseColor=texture2D(U_MainTexture,M_coord);gl_FragColor=max(blendColor,baseColor);}


变暗shader

uniformsampler2DU_MainTexture;uniformsampler2DU_SubTexture;varyingvec2M_coord;voidmain(){vec4blendColor=texture2D(U_SubTexture,M_coord);vec4baseColor=texture2D(U_MainTexture,M_coord);gl_FragColor=min(blendColor,baseColor);}