Also can you confirm vertex (rather than fragment) shader is optional?
On Jun 27, 2015 8:56 AM, "Raul Miller" <[email protected]> wrote:
> 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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