[SDL] Help with SDL 1.3 and OpenGL 3.3/GLSL3.3core
alex.barry at gmail.com
Fri Nov 18 19:14:07 PST 2011
Hi, me again,
So, now I've debugged the crap out of my OpenGL code, and rooted out all
the errors, but I still have the misfortune of having nothing rendered to
Any help reviewing my code would be greatly appreciated. If this is out of
scope for the SDL mailing list, I understand, and I'll repost in a more
Thanks ladies and gents,
On Fri, Nov 18, 2011 at 12:50 PM, Alex Barry <alex.barry at gmail.com> wrote:
> So, the shader issue was glew's experimental option gone wrong, so I
> stopped using that, (the call was glewExperimental = GL_TRUE; in
> sdlapp.cpp:51, for those interested). I was still getting rendering
> issues, but it turns out the issue is that I need a bound VAO (vertex array
> object), so I got that, and I think I have it sorted out.
> Thanks for the help, Forest,
> On Thu, Nov 17, 2011 at 6:22 PM, Alex Barry <alex.barry at gmail.com> wrote:
>> So, i just put in a crap load of glGetError checks, and here is the
>> problem (glshader.cpp:77-78):
>> this->shader_vp = glCreateShader(GL_VERTEX_SHADER);
>> undeadland::logEnterFromGlError( glGetError(),
>> "(glshader.cpp:77->glCreateShader)" );
>> I get an error about the enumeration value, GL_VERTEX_SHADER, which is
>> the correct value, according to
>> Did I miss something to be able to use GL_VERTEX_SHADER?
>> Any help would be appreciated,
>> On Thu, Nov 17, 2011 at 3:17 PM, Forest Hale <havoc at ghdigital.com> wrote:
>>> I briefly glanced at the code and don't notice anything out of the
>>> ordinary at a glance, but why are you not checking glGetError() after each
>>> gl call? It is often the first step in debugging OpenGL problems.
>>> If you were not targeting GL3.3core I would suggest doing some simpler
>>> debugging tests with glBegin and such.
>>> In any case these are the usual suspects:
>>> glClear - make sure your glDepthMask and glColorMask and glStencilMask
>>> and such are TRUE before you clear the corresponding buffer bit or it won't
>>> glScissor - make sure your glScissor includes the area you wish to
>>> render into, if GL_SCISSOR_TEST is enabled at least.
>>> glUniformMatrix - make sure your matrix is good, and not transposed.
>>> glColorMask/glDepthMask/**glStencilMask - make sure you have the write
>>> masks enabled that you think you do :)
>>> When in doubt I often fall back to reproducing the same intended result
>>> by other means, like doing a screen coordinate transform in software
>>> (equivalent to gluProject stuff) to make sure I have everything right
>>> (checking if the pixel coords are in bounds, etc).
>>> On 11/17/2011 08:41 AM, Alex Barry wrote:
>>>> I don't know if this is the right place to post this, as it's not
>>>> necessarily an SDL issue, but I'm stuck trying to render a land-mesh, which
>>>> for some reason just won't render.
>>>> I have the project on github, and it can be found here:
>>>> https://github.com/mrozbarry/**procworld<https://github.com/mrozbarry/procworld>(if you see any code you like, you can steal it - I currently don't have a
>>>> license for this source, so
>>>> while the getting is good... :P)
>>>> So, I was originally doing a huge triangle mesh to try and render that,
>>>> and I got frustrated with it, so I re-coded it into a point cloud, just to
>>>> get the rendering done, and it still doesn't work.
>>>> The opengl/sdl code is spread between a few different files:
>>>> * sdlapp.* has most of the SDL centric code in it - I don't think
>>>> the issue is here, but maybe I'm wrong...
>>>> * glshader.* has the shader loading/validation routines, which also
>>>> seems to work fine
>>>> * landscape.* generates the landscape, and has the rendering routine
>>>> in it
>>>> * camera.* has most of the matrix transforms in it
>>>> I've been banging my head over this for a few days, and can't get
>>>> anything to render at all. What's more frustrating is that I am helping
>>>> convert some of the tutorials from
>>>> http://www.opengl-tutorials.**org/ <http://www.opengl-tutorials.org/>, and I'm using a similar sdlapp setup, and it works perfectly, and
>>>> everything displays.
>>>> I'll be the first to admit that I'm not a guru or anything in OpenGL,
>>>> and especially GLSL (the only opengl i've done up to this point has been
>>>> OpenGL 1.1), so any help would be great.
>>>> Take care, gents,
>>>> SDL mailing list
>>>> SDL at lists.libsdl.org
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>>> darkplaces <http://icculus.org/twilight/darkplaces>
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