线性/非线性纹理映射扭曲的四边形 [英] Linear/Nonlinear Texture Mapping a Distorted Quad
问题描述
在我的上一个问题中，可以确定当对四边形进行纹理处理时，面部分解成三角形，并以仿射的方式插值纹理坐标.
In my previous question, it was established that, when texturing a quad, the face is broken down into triangles and the texture coordinates interpolated in an affine manner.
不幸的是，我不知道该如何解决. 提供的链接很有用，但效果不理想.作者得出结论:请注意，图像看起来好像是一个长的矩形四边形，一直延伸到远处……由于它产生的错误的深度感知"，它可能会变得相当混乱……".
Unfortunately, I do not know how to fix that. The provided link was useful, but it doesn't give the desired effect. The author concludes: "Note that the image looks as if it's a long rectangular quad extending into the distance. . . . It can become quite confusing . . . because of the "false depth perception" that this produces."
我想做的是使纹理保留纹理的原始缩放比例.例如，在梯形的情况下，我希望纹理像素的垂直间距是相同的(使用paint程序创建的示例):
请注意，由于垂直间距相同，但四边形具有明显的变形，因此纹理空间中的直线不再是世界空间中的直线.因此，我认为所需的映射是非线性的.
What I would like to do is to have the texturing preserve the original scaling of the texture. For example, in the trapezoidal case, I want the vertical spacing of the texels to be the same (example created with paint program):
Notice that, by virtue of the vertical spacing being identical, yet the quad's obvious distortion, straight lines in texture space are no longer straight lines in world space. Thus, I believe the required mapping to be nonlinear.
问题是:在固定功能管道中这是否有可能?我什至不确定确切的答案对于更通用的四边形是什么.我认为插值函数很快就会变得非常复杂，并且我意识到保留原始比例"并不是一种精确的算法.世界空间三角形在纹理空间中不再是线性的.
The question is: is this even possible in the fixed function pipeline? I'm not even sure exactly what the "right answer" is for more general quads; I imagine that the interpolation functions could get very complicated very fast, and I realize that "preserve the original scaling" isn't exactly an algorithm. World-space triangles are no longer linear in texture space.
顺便说一句，我真的不理解第3 rd 和第4 纹理坐标；如果有人可以指向我提供资源，那就太好了.
As an aside, I do not really understand the 3rd and 4th texture coordinates; if someone could point me to a resource, that would be great.
推荐答案
可以在Nathan Reed的博客中找到使用现代gpu-api的解决方案的最佳方法
The best approach to a solution working with modern gpu-api's can be found on Nathan Reed's blog
http://www.reedbeta.com /blog/2012/05/26/quadrilateral-interpolation-part-1/
但是您最终会遇到一个与原始问题类似的问题:(我尝试解决它，并在获得解决方案后发布解决方案.
But you end up with a problem similar to the original problem with the perspective :( I try to solve it and will post a solution once i have it.
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