[PD] use gl_VertexID

[Philippe Boisnard]

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 at 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 <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 <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 <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 at 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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>> 
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