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GLSL片段着色器中纹理到对象的纯映射

[英]Plain mapping of texture to object in GLSL fragment shader

原文 2011-12-11 12:40:30 7 1 opengl/ glsl/ textures/ texture-mapping/ fragment-shader

I have a problem with mapping of texture in fragment shader. 我在片段着色器中映射纹理时遇到问题。 I have a texture that has same size as window (I use part of scene rendered in previous pass, but I use brick texture in the example below) and I need to map it as in 2D. 我有一个与窗口大小相同的纹理（我使用前一个渲染中渲染的场景的一部分，但我在下面的示例中使用了砖纹理），我需要将其映射为2D。 Is it somehow possible ? 它有可能吗？ I tried different ways, but nothing worked. 我尝试了不同的方法，但没有任何效果。

Could you please advice me how should the fragment shader looks like ? 你能告诉我片段着色器应该怎么样？ Please any advice will be helpfull. 请任何建议都有帮助。 Thank you! 谢谢！

带有普通映射的tepaot

1 个解决方案

I have a texture that has same size as window (…) and I need to map it as in 2D. 我有一个与窗口大小相同的纹理（...），我需要将其映射为2D模式。

So if I understand you correctly, then you want to use the previously generated texture as if it was some kind of "layer", where texture pixels map 1:1 to viewport pixels, and the texture has the very same size like the viewport? 因此，如果我对您的理解正确，那么您想使用先前生成的纹理，就好像它是某种“图层”一样，其中纹理像素将1：1映射到视口像素，并且纹理具有与视口相同的大小？

If so then this is very easy (as of GLSL version 1.30). 如果是这样，那么这非常容易（从GLSL版本1.30开始）。 There is the function texelFetch , which takes a pixel index as coordinate (unlike texture which takes a value in the range [0; 1]). 有一个texelFetch函数，它将一个像素索引作为坐标（与采用[0; 1]范围内的值的texture不同）。 The built in variable gl_FragCoord gives the window coordinates of the currently processed fragment. 内置变量gl_FragCoord给出当前处理的片段的窗口坐标。 So by using the coordinates in gl_FragCoord for texelFetch you get the desired result. 因此，通过将gl_FragCoord的坐标用于texelFetch您可以获得所需的结果。