使用着色器中的索引引用数据纹理中的纹素 [英] Referencing texels in a data texture using indexes in the shader

问题描述

我尝试使用着色器中的索引访问 DataTexture 的纹素中的值.索引[0, 1, 2, 3, 4, 5, 6... 62, 63] 是连续的，而数据纹理有高度和宽度(uTextureDimension) of 8. 经过一番研究，我写了这个函数来获取特定的索引值，并引用相应的纹素:

I have values in the texels of a DataTexture that I am trying to access using indexes in my shader. The indexes [0, 1, 2, 3, 4, 5, 6... 62, 63] are continuous, while the data texture has a height and width (uTextureDimension) of 8. After some research I wrote this function to take a particular index value, and reference the corresponding texel:

vec2 customUV = vec2( mod(aIndex, uTextureDimension) / uTextureDimension, floor(aIndex / uTextureDimension) / uTextureDimension );
vec4 texelValues = texture2D( tDataTexture, customUV ).xyzw;

我也试过这个版本从它的中心点引用纹素.也没有骰子:

I also tried this version to reference the texel from its center point. Also no dice:

vec2 perMotifUV = vec2( mod( aIndex, uTextureDimension ) * (( 1.0 / uTextureDimension )/2.0), floor( aIndex / uTextureDimension ) * (( 1.0 / uTextureDimension )/2.0) );
vec4 texelValues = texture2D( tDataTexture, customUV ).xyzw;

从昨天下午开始处理这个问题，在这里和那里编辑它，并四处寻找其他解决方案，我仍然没有得到预期的结果.我应该说在使用 Three.js 时，着色器被设置为高精度浮点数 - 这是问题的一部分吗?任何人都可以在这里推动我走上正轨吗?谢谢！

After working with this since yesterday afternoon, editing it here and there, and looking around for other solutions, I'm still not getting the expected results. I should say that in using Three.js, the shaders are set to high precision float - is this part of the problem? Can anyone nudge me on track here? Thanks!

推荐答案

第一个似乎是对的，如果一切都是浮动的.您是否使用 NEAREST 过滤器模式?从技术上讲，您还应该添加一个半纹素大小的偏移量:

The first one seems right, if everything is a float. Are you using NEAREST filter mode? Technically you should also add a half-texel-size offset too:

vec2 texelSize = 1.0 / uTextureDimension;
vec2 customUV = vec2( mod(aIndex, uTextureDimension)*texelSize, floor(aIndex / uTextureDimension)*texelSize );
customUV += vec2(0.5*texelSize);

编辑 - 你的指数也应该是 0-63 而不是 0-64

EDIT - Also your indices should go 0-63 not 0-64

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