That's an interesting clue. Thank you.
But I'm still not understanding something important. For example, this
still renders black:
require 'graphics/gl2 api/gles'
coinsert 'jgl2 jgles'
FORM=: 0 : 0
pc form closeok;
minwh 320 240; cc gl opengl flush;
)
fshader=: 0 :0
#version 110
void main(void) {
gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}
)
form_run=: 3 : 0
wd FORM
wd 'pshow'
)
form_gl_initialize=: 3 : 0
smoutput 'initializing'
smoutput wglGLSL''
'err program'=: gl_makeprogram '';fshader
if.#err do.
smoutput 'fail'
smoutput err return. end.
glUseProgram program
)
form_gl_paint=: 3 : 0
smoutput 'painting'
)
form_run''
The output I get is:
initializing
450
painting
painting
(I also am wondering where that blank line is coming from...)
Thanks,
--
Raul
On Fri, Jun 26, 2015 at 8:44 PM, bill lam <[email protected]> wrote:
> you run opengl functions in form_run but opengl context has not yet
> available at that point. try put them inside the initialize callback. see
> the shader.ijs demo.
>
> you can query the version of shader langauge in the initialize callback and
> determine whether you need the #version header.
> On Jun 27, 2015 8:28 AM, "Raul Miller" <[email protected]> wrote:
>
>> I am trying to implement a minimal example of using a shader within J.
>>
>> This means: no vertex shader. I just want to paint the screen a solid
>> color.
>>
>> This means: no #version header (which I believe is equivalent to #version
>> 110).
>>
>> Unfortunately, while this should work in principle, a number of
>> variations on the implementation have not worked for me.
>>
>> I can show that opengl is working, using the glClear mechanism, but
>> while that accomplishes the "set the screen to a single color"
>> subtask, it does not get me my minimal shader which was the point of
>> the exercise.
>>
>> Here's an example:
>>
>> load 'pacman'
>> 'install' jpkg 'graphics/gl2 api/gles'
>> require 'graphics/gl2 api/gles'
>> coinsert 'jgl2 jgles'
>>
>> FORM=: 0 : 0
>> pc form closeok;
>> minwh 320 240; cc gl opengl flush;
>> )
>> fshader=: 0 :0
>> void main(void) {
>> gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
>> }
>> )
>> form_run=: 3 : 0
>> wd FORM
>> 'err program'=: gl_makeprogram '';fshader
>> if.#err do. smoutput err return. end.
>> wd 'pshow'
>> gl_paint ''
>> )
>> form_gl_paint=: 3 : 0
>> smoutput 'painting'
>> glClearColor 0 0 1 1
>> glClear GL_COLOR_BUFFER_BIT + GL_DEPTH_BUFFER_BIT
>> glUseProgram program
>> )
>> form_run''
>>
>> Now...
>>
>> Part of the problem is that I do not know what is happening in libjqt,
>> and those entry points are not documented. But I do not necessarily
>> need that, I hope, not right now anyways.
>>
>> Anyways, if I eliminate the glClearColor and glClear statements, the
>> image is black. But if the shader were to be used, the image would be
>> red.
>>
>> How do I make this work?
>>
>> Thanks,
>>
>> --
>> Raul
>> ----------------------------------------------------------------------
>> For information about J forums see http://www.jsoftware.com/forums.htm
>>
> ----------------------------------------------------------------------
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