Weird Terrain Depth Issue with new OpenGL Versions

OpenGL OpenGL: Advanced Coding
1

Hi!

I´m having a weird rendering problem with my Objects , mainly with my terrain object, that seems to be a depth problem.
This issue starts when i update my GPU drivers to OpenGL versions greater than 4.3.

I put in youtube a little video showing the issue for better understanding! :wink:

This is the history of the problem:

01 - I start use a AMD R9 280X to develop my 3D aplication with the original driver that come with the GPU(Version 4.3)
Everyting was being rendered ok, including my terrain object.
02 - When i first update my GPU AMD drivers(4.4 and after 4.5) , a issue with the depth happen.
03 - I send the problem to AMD check it out if its not a problem with the driver, and they answer to me becouse is the same program it seems a problem with the driver and they will check it out…
04 - I install the original driver again and still developing the solution.
05 - I buy a new GPU but now a NVIDIA GTX 960.
06 - After a clean clean installation of the new GPU (With the card and AMD drivers completely removed) , i test the same program and the same issue happen!

So, looking at the history of the problem, it seems something removed in the new versions of OpenGL , and now i need take a path to solve it…

I see in the Redbook something related to OIT , that make possible be implemented in the fragment shader as a depth test to render the pixels, but i need to know if there is another solution with less work to do than re-implement something that the driver do in the past just with an enable command! :wink:

Anyone have an idea of the best choices to solve the problem showed in the video?

PS:. I not put any code here yet, becouse in fact acctually i´m only using the default depth configuration enabling it and refreshing at every frame using the Clear and enable funcions.

Any help will be much appreciated!

Kind Regards.

2

Hi!

Finally i find out the root cause of the problem.

Basically when i´m rendering all the frames i enable/disable the buffers like this:

//Enable States
pGL->glEnable     (GL_DEPTH_TEST    );
pGL->glEnable     (GL_BLEND         );
pGL->glEnable     (GL_CULL_FACE     );
pGL->glEnable     (GL_TEXTURE_2D    );
pGL->glClear     ( GL_COLOR_BUFFER_BIT  |
                       GL_DEPTH_BUFFER_BIT  |
                       GL_ACCUM_BUFFER_BIT  |
                       GL_STENCIL_BUFFER_BIT);

pGL->glPolygonMode(GL_FRONT,GL_FILL );
pGL->glCullFace   (GL_BACK          );
pGL->glDepthFunc  (GL_LESS          );
//pGL->glDepthMask  (GL_TRUE          );


//Disable States
pGL->glDisable     (GL_DEPTH_TEST   );
pGL->glDisable     (GL_CULL_FACE    );
pGL->glDisable     (GL_TEXTURE_2D   );
pGL->glDisable     (GL_BLEND        );
//pGL->glDepthMask   (GL_FALSE        );

When i disable the call of glDepthMask , the problem stop, and the things start to work again.
In fact debbuging the code, since now all the rendering commands and states are assinchronous and i´m not using Sync objects, before the terrain rendering finish…the Depth Buffer was disabled…

So…the solution of the problem was find, but yet i have a doubt why the version 4.3 works and the other versions not, i will check it out my version pointers.

Anyway, please consider this issue solved , and the problem was in my own code.

Kind Regards.