opengl - 向量在着色器语言中如何相乘？

Question

比如gl_FragColor = v1 * v2，我无法真正理解它是如何相乘的，似乎引用文献给出了向量乘法矩阵的解释。
ps:v1和v2的类型均为vec4。

Answer 1

* 运算符有效 component-wise对于像 vec4 这样的向量。

vec4 a = vec4(1.0, 2.0, 3.0, 4.0);
vec4 b = vec4(0.1, 0.2, 0.3, 0.4);
vec4 c = a * b; // vec4(0.1, 0.4, 0.9, 1.6)

GLSL Language Specification 5.10 向量和矩阵运算部分说:

With a few exceptions, operations are component-wise. Usually, when an operator operates on a vector or matrix, it is operating independently on each component of the vector or matrix, in a component-wise fashion. [...] The exceptions are matrix multiplied by vector, vector multiplied by matrix, and matrix multiplied by matrix. These do not operate component-wise, but rather perform the correct linear algebraic multiply.