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Member Since 18 Nov 2005
Offline Last Active Mar 27 2015 03:22 PM

Topics I've Started

Dynamic Tessellation Control

04 March 2015 - 02:19 PM

I'm about to step into turning tessellation on and playing around with it for the first time. The one issue I have is that there are two types of bricks:






The difference is that the modern flat ones only need to be tessellated around the rectangle edges. The inside of the brick doesn't actually need to be tessellated because it is flat and tessellating it will add no surface detail.


Is this something that should be done in a geometry shader then? Where I can send a texture that is a heat map for where/how much tessellation to perform? Is there already support or planned support for this?


Toggling Between Video Cards

08 February 2015 - 12:19 AM

Pretty sure the answer to this was no and probably still is. There are motherboards that used to have bios settings or whatever for onboard video card disabling so I assume a bios switch or something might exist.


I would like to buy a new video card for development reasons only, as the one I have now runs all games on high so I don't need to drop 250.00 on a newer card.


I only want to buy it though, if I can toggle between my old and new card. So I have 2 benchmarks for my games performance on an old card and new card. Whether I have to restart the computer, or do something in the bios each time would be fine. I just don't want to have to plug one in, update drives, run my game + benchmark. Swap the old graphics card physically. Install drivers. Benchmark.


Is this possible to have 2 plugged in and choose between them?

glTexSubImage3D, invalid enum

06 February 2015 - 02:44 PM

Short and sweet, I get an invalid ENUM on the "glTexSubImage3D()"
This works on my ATI card but not on NVidia. I've re-read the docs several times. My enums look good.

GLenum pixelFormat = GL_RGB;

GLuint GL_Index;
//Allocate the storage.
glTexStorage3D(GL_TEXTURE_2D_ARRAY, numMipMapLevels, pixelFormat, textureSize, textureSize, textures.size());


for(int i = 0; i < textures.size();i++)

            Texture* texutre = textures[i];

const int mipLevelUploading = 0;
        const int depth = 1;
        glTexSubImage3D(GL_TEXTURE_2D_ARRAY, mipLevelUploading, 0, 0, i, diffuseTextureSize, diffuseTextureSize, depth, pixelFormat, GL_UNSIGNED_BYTE, texture->pixels);
        GLenum error = glGetError();



Bus Bandwidth

04 February 2015 - 02:23 PM

Back when I first started openGL 8 years ago, I had the naive:



for(int i = 0; i < vertices; i++)


glNormal(); glTexCoord2f();glVertex();




I used to do this with some models that were 10,000 verts or so, I remember running gDebugger and having 100,000 + openGL function calls.


Now I was doing a test on a scene with 4000 objects (the same six objects duplicated 800 times). I internally track redundant state changes and I only bind the objects once, and draw them all. My test case there isn't much pixel overdraw. Here I have only 5000 openGL function calls.


Anyway, back on that old video card I still used to get like 60FPS or so from what I remember, Now I may have only had 50 objects in my scene back then and I now have 4000, but my total openGL calls today per frame is 5,000. Back then it was 100,000+.

Clearly I have a much better motherboard, much faster bandwidth, and way less openGL function calls (but I do have a lot more draw calls). So if it isn't a bandwidth issue, what is slowing down the GPU so much? What is going on internally, clearly doesn't seem to be a bandwidth issue. What happens when the draw() command hits that destroys everything?

Parallax Corrected Cube Maps

30 January 2015 - 08:45 PM

I'm talking about this technique if you don't know about it. What I'm wondering though, is what if my scene is outdoors and I have cars and not just 4 building on each side of me, then I can't approximate the walls of my cube map and perform this ray to cube map type intersection. Has anyone tried this with a more unique world scene?