法线矩阵 在很多顶点shader中都用到了gl_NormalMatrix。这里将介绍这个矩阵是什么,以及它的作用。 大部分计算是在视图空间内完成的,主要原因是光照的运算要放在这个空间内,否则一些依赖观察点坐标的效果,比如镜面反射光就很难实现。 所以我们需要将法线变换到视图空间。变换一个顶点到视图空间的方法如下: vertexEyeSpace...
在Direct3D你不需要关心这些,因为都处理好了,所以一路稀里糊涂下来效果也基本上做的出来,在OpenGL就不行了。下面解释了什么是 gl_NormalMatrix,简而言之gl_NormalMatrix是为了令法线在perspective projection之后和投影后的模型平面依然垂直,但是它并不是投影矩阵哦,而是投影矩阵的逆矩阵的翻转矩阵 。呵呵,顺便想象下投...
b-a) == transpose(n) * (a-b) == 0. In fact, the only difference is the new matrices wedged in the middle. If we pick N to make the term in the middle the identity, then our new normal will be perpendicular to the surface too:...
> I think we could make a more general piglit test the reproduce this > sort of failure. Attached is a new patch against piglit master. I took the approach of generating the shader instead of uniforms, because I perceived it to be easier to specify .x, .y, and .z as the gl_Normal...
> > was smaller than 0.0, but larger than 0-epsilon for some small > > epsilon, similar to gl_NormalMatrix[1].z on intel but in the > > opposite direction. > > > > I spot-checked gl_NormalMatrix[2].y with LIBGL_ALWAYS_SOFTWARE=1. ...
The eigenvalues of the matrix...doi:10.1140/epjp/s13360-022-03334-xBclea, DianaDepartment of Mathematics and Computer Science, Lucian Blaga University of Sibiu, Sibiu, RomaniaSpringer Berlin HeidelbergThe European Physical Journal Plus
关于为什么对法线变换时要使用变换矩阵的转置的逆,而不能像变换顶点那样直接使用变换矩阵 https://www.cnblogs.com/bigdudu/articles/4191042.html 注意文章中风格是opengl的,即矩阵X向量,而不是 向量X矩阵形式。 同时也遵守:向量默认为列向量,列向量的转置为行向量,行向量乘列向量为一个数值等价于二者的DOT...
//但为什么不能直接转换方向向量呢?因为方向向量只有三个分量,但我们可以用下面的代码解决 normalEyeSpace = vec3(gl_ModelViewMatrix * vec4(gl_Normal,0.0)); So,gl_NormalMatrixis just a shortcut to simplify code writing? No, not really. The above line of code will work in some circunstances...
nvidia intel [ 1.0 0.0 0.0 ] [ 1.0 0.0 0.0 ] [ 0.0 -0.0 1.0 ] [ 0.0 0.0 >0.0, <0.0001 ] [ 0.0 -1.0 -0.0 ] [ 1.0 15.0 0.0 ] I used "-0.0" for a couple slots on the nvidia system; the value was smaller than 0.0, but larger than 0-epsilon for some small epsilon, ...
> driver. I don't quite understand the interaction between drm, the > kernel, X proper, and Mesa to know what needs to be compiled, nor have > I ever found good documentation on how to swap out my driver on either > mesa3d.org or intellinuxgraphics.org. ...