Question

我想使用片段着色器使用着色器将RGB转换为YUV420P。

1，我想出了当前纹理颜色的坐标。

2，我计算了4 Y并将其置于当前颜色。

我的代码：

    precision mediump float;
    varying vec2 vTextureCoord;
    uniform sampler2D tex;
    uniform float width;
    uniform float height;
    uniform float offset;
    uniform vec3 scal;

    void main(void) {
        vec2 nowTxtPos = vTextureCoord;
        vec2 size = vec2(width, height);
    // y
        if(nowTxtPos.y<0.25){
    // y1 postion
            vec2 now_pos = nowTxtPos * size;
            vec2 basePos = now_pos * vec2(4.0,4.0);
            float addY = float(int(basePos.x / width));
            basePos.x = basePos.x - addY * width;
            basePos.y += addY;

            float y1,y2,y3,y4;
            vec2 samplingPos = basePos / size;
            vec4 texel = texture2D(tex, samplingPos);
            y1 = dot(texel.rgb, scal);
            y1 += offset;

            basePos.x+=1.0;
            samplingPos = basePos/size;
            texel = texture2D(tex, samplingPos);
            y2 = dot(texel.rgb, scal);
            y2 += offset;

            basePos.x+=1.0;
            samplingPos = basePos/size;
            texel = texture2D(tex, samplingPos);
            y3 = dot(texel.rgb, scal);
            y3 += offset;

            basePos.x+=1.0;
            samplingPos = basePos/size;
            texel = texture2D(tex, samplingPos);
            y4 = dot(texel.rgb, scal);
            y4 += offset;

            gl_FragColor = vec4(y1, y2, y3, y4);
        }
    }

图片（YUV420P）：

picture

Enlarged post picture

它有别名。我不知道为什么。

Answer 1

我已经解决了。因为计算精度不够。

在这里编辑：

＆＃34;精准中介浮动;＆＃34; - ＆GT; ＆＃34;精度highp float;＆＃34;

使用着色器

1 个答案: