o use gl_VertexID with #version 120 
it ’s necessar to indicate #extension :
#extension GL_EXT_gpu_shader4 : require

Le 14 juin 2018 à 13:12, Claude Heiland-Allen <claude@mathr.co.uk> a écrit :

Hi Philippe,

On 14/06/18 10:51, Philippe Boisnard wrote:
I continue to search to use gl_VertexID

when I want to declare a version in vertex shader script, I want to declare for example
#version 2.1 (it’s the openGL version when I check with print gemwin)
but I have this in the PD_Terminal
ERROR: 0:1: '' :  version '2' is not supported

The GL/GLSL version numbering is a bit obscure:

https://stackoverflow.com/questions/19021567/finding-supported-glsl-version#19022416

For OpenGL 2.1 you need this as first line of your shader:

#version 120

The good news is that gl_VertexID is supported in almost all GLSL versions:

http://docs.gl/sl4/gl_VertexID

For OpenGL ES (as found on embedded devices, eg mobile phones) you might not be so lucky:

http://docs.gl/el3/gl_VertexID

But I don't know if Gem supports attribute-less rendering (ie, just using gl_VertexID without any vertex data or element index buffers).


Claude
Can I  use a version 2 for a vertex shader ?

if I don’t declare a version
gl_VertexID is not recognized

Philippe



Le 14 juin 2018 à 06:27, Philippe Boisnard <philemon1@mac.com> a écrit :


Hello

I have a question about shader
I search to work with gl_VertexID in .vert script.
Some one have an example to implement this in .vert.
With gl_VertexID, you can have an array of vertex with no input array for VBO and you can detreminate in real time the size of VertexArray with no latencies.
I know that we can use this, but I have difficulties.

best regards

Philippe
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