Why not vec3 for OpenGL ES 2.0 gl
I am new to OpenGL ES 2.0, and cannot understand the following simplest shader:
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?
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.
By default, this should be set to 1.0.
See here for some more info: http://web.archive.org/web/20160408103910/http://iphonedevelopment.blogspot.com/2010/11/opengl-es-20-for-iOS-chapter-4.html
如果直接在剪辑空间中将顶点提供给着色器，则只需传递x，y，z并在该着色器中添加1作为w组件。
attribute vec3 vPosition; // vec3 instead of vec4
void main()
{
gl_Position = vec4 (vPosition, 1.0);
}
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