OpenGL: Add vertices with vertex shader

Question

Tell me, please, how I can add new vertex in vertex shader?

score 7 · Accepted Answer · answered Apr 28 '11 at 15:37

7

The vertex shader only transforms vertices. If you need to output additional geometry based on the input vertices a geometry shader is what you need.

answered Apr 28 '11 at 15:37

pmr

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score 3 · Answer 2 · answered Apr 28 '11 at 15:37

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You can add vertices using a geometry shader http://www.opengl.org/wiki/Geometry_Shader

"A GS can create new primitives, unlike vertex shaders, which are limited to a 1:1 input to output ratio."

answered Apr 28 '11 at 15:37

Roy T.

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score 3 · Answer 3 · answered Apr 28 '11 at 15:38

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You can't. That's what geometry shaders are for.

answered Apr 28 '11 at 15:38

genpfault

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score 0 · Answer 4 · answered Aug 10 '21 at 13:06

It's not possible to create new vertices using a vertex shader; it can only transform vertices. The Khronos documentation for the vertex shader states:

A vertex shader receives a single vertex from the vertex stream and generates a single vertex to the output vertex stream. There must be a 1:1 mapping from input vertices to output vertices.

There are several options for adding new vertices:

Generate the new vertices on the CPU before rendering them.
Use a geometry shader for creating new vertices based on a given primitive.
Use tessellation for creating new vertices based on a given patch.

OpenGL: Add vertices with vertex shader

4 Answers4