为什么不为OpenGL ES 2.0 gl_Position提供vec3呢?

I am new to OpenGL ES 2.0, and cannot understand the following simplest shader:

我是OpenGL es2.0的新手，无法理解以下最简单的着色:

attribute vec4 vPosition;
void main()
{
   gl_Position = vPosition;
}

My question is, since a position would be a vector of (x, y, z), why is gl_Position a vec4 instead of vec3?

我的问题是，既然位置是向量(x, y, z)为什么gl_Position是向量4而不是向量3?

2 个解决方案

The w in vec4(x, y, z, w) is used for clipping, and plays its part while linear algebra transformations are applied to the position.

w在vec4(x, y, z, w)中用于裁剪，并发挥其部分，而线性代数变换应用于该位置。

By default, this should be set to 1.0.

默认情况下，应该将其设置为1.0。

更多信息请参见这里:http://web.archive.org/web/201608103910/http://iphonedevelopment.blogspot.com/2010/11/opengl-es-20-for ios-chapter -4.html

If you provide your vertices to the shader directly in clip space, you could just pass x,y,z and add 1 as the w component in that shader.

如果你在剪辑空间中直接向着色器提供你的顶点，你可以通过x,y,z和添加1作为那个着色器中的w元素。

attribute vec3 vPosition; // vec3 instead of vec4
void main()
{
   gl_Position = vec4 (vPosition, 1.0);
}