完整代码查看# AndroidShaderDemo下的FlashWhiteRender

有了之前的缩放特效，闪白就很容易了，闪白的原理就是在原像素rgb分量上加个[0,1]之间的参数。

fragment shader如下:

precision mediump float;
uniform sampler2D u_TextureUnit;
varying vec2 v_TextureCoordinates;

uniform float texelWidthOffset;
uniform float texelHeightOffset;

uniform float uflashParam;
void main()
{
   vec4 fragColor = texture2D(u_TextureUnit, v_TextureCoordinates);

   gl_FragColor = vec4(fragColor.r + uflashParam,fragColor.g + uflashParam,fragColor.b + uflashParam,fragColor.a);
}

uflashParam就是加的参数，由每帧的index决定，具体代码为:

private void prepareDraw(){
        float progress;
        if (curFrame <= MiddleFrame) {
            progress = curFrame * 1.0f / MiddleFrame;
        } else {
            progress = 2f - curFrame * 1.0f / MiddleFrame;
        }

        glUniform1f(flashWhiteProgram.getFlashAttributeLocation(), progress);

        curFrame++;
        if(curFrame > MaxFrame){
            curFrame = 0;
        }
    }

最后效果如下：

flash_white.gif