GLSL 着色器不需要的灰度效果

Question

让我以我对 GLSL 非常陌生的事实作为序言。

我正在尝试使用着色器在插槽卷轴符号旋转时添加模糊效果。我有一个正在运行的模糊效果，为了简单起见，我将其注释掉并隔离了这个问题。

顶点着色器:

//Vertex Shader
attribute vec4 position;
attribute vec4 inColor;
attribute vec2 inUV;

//To be passed to the Fragment Shader "BlurShader.fsh"
varying vec4 colorVarying;
varying vec2 uvOut;

void main()
{
    colorVarying = inColor;
    gl_Position = position;
    uvOut = inUV;
}

片段着色器:

//Fragment Shader

uniform sampler2D tex0;

//Passed from Vertex Shader "BlurShader.vsh"
varying vec4 colorVarying; //ISSUE: this is always solid white
varying vec2 uvOut;

//This is the intensity of the blur. Higher is a larger blur
//  25 is a good starting point
//  Could possibly make it a varible to be passed in to control directly from Lua
#define INTENSITY 25.0

vec4 BlurVertical(vec2 size, vec2 uv, float radius) {
    if (radius >= 1.0)
    {
        vec4 C = vec4(0.0); 
        float height = 1.0 / size.y;
        float divisor = 0.0; 

        for (float y = -radius; y <= radius; y++)
        {
            C += texture(tex0, uv + vec2(0.0, y * height));
            divisor++; 
        }
        return vec4(C.r / divisor, C.g / divisor, C.b / divisor, 1.0);
    }
    return texture2D(tex0, uv);
}

void main()
{
    //Apply blur to final output
    //gl_FragColor = BlurVertical(textureSize(tex0, 0), uvOut, INTENSITY);
    //gl_FragColor = texture2D(tex0, uvOut) * colorVarying; SAME RESULT
    gl_FragColor = texture2D(tex0, uvOut);
}

我的问题是着色器会导致奇怪的不需要的灰度效果和透明度损失。

奇怪的灰度效果

它应该是什么样子

我对可能导致此问题的原因感到非常困惑，而且我似乎找不到任何有类似问题的人。

Answer 1

找到解决方案了!我使用的纹理是用 YUVA 编码的，所以实际上我需要采样 4 个纹理，然后转换为单个 RGBA。

uniform sampler2D tex[4];

vec4 YUVAtoRGBA() 
{
    mat4 xForm = mat4(
        1.164, 1.164, 1.164, 0.0,
        0.0, -0.391, 2.018, 0.0,
        1.596, -0.813, 0.0, 0.0,
        0.0, 0.0, 0.0, 1.0);

    vec4 yuva = vec4(
        texture2D(tex[0], (uvOut.xy / uvOut.z).x - 0.0625,
        texture2D(tex[1], (uvOut.xy / uvOut.z).x - 0.5,
        texture2D(tex[2], (uvOut.xy / uvOut.z).x - 0.5,
        texture2D(tex[3], (uvOut.xy / uvOut.z).x);

    return colorVarying * (xForm * yuva);
}