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Type: Posts; User: Budric

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1. ## Thread: VBO - non interleaved {vertex, color, texCoord, n}

by Budric
Replies
7
Views
2,487

### Re: VBO - non interleaved {vertex, color, texCoord, n}

One color was a bit of an oversimplification to make a point.

For a small set of colors - say 1000 verticies and 2 colors. I could pass an index with each vertex, and a bound texture as a...
2. ## Thread: VBO - non interleaved {vertex, color, texCoord, n}

by Budric
Replies
7
Views
2,487

### Re: VBO - non interleaved {vertex, color, texCoord, n}

I see. That's a shame.

Is aligning to 32 byte necessary or is that dated information?
3. ## Thread: VBO - non interleaved {vertex, color, texCoord, n}

by Budric
Replies
7
Views
2,487

### VBO - non interleaved {vertex, color, texCoord, n}

Hi,
I'm learning/adjusting to the new 3.0+ standard. I've been reading tutorials and wikis. The approach presented in the wiki (http://www.opengl.org/wiki/Vertex_Buffer_Objects) and this tutorial...
4. ## Thread: 3D object/plane intersection contour

by Budric
Replies
7
Views
9,309

### Re: 3D object/plane intersection contour

This post discusses how to determine whether a diagonal is inside a polygon: http://stackoverflow.com/questions/69383...concave-polygon

I could use that to post process my results. It's going to...
5. ## Thread: 3D object/plane intersection contour

by Budric
Replies
7
Views
9,309

### Re: 3D object/plane intersection contour

Rosario Leonardi, yes that's the problem I'm trying to solve. The problem with using GL_LINES is that it still doesn't produce the output I want in certain corner cases. For example if the table...
6. ## Thread: 3D object/plane intersection contour

by Budric
Replies
7
Views
9,309

### Re: 3D object/plane intersection contour

Well the line (1,0), (0,1) is drawn which I don't want. Any way to get rid of that?
7. ## Thread: 3D object/plane intersection contour

by Budric
Replies
7
Views
9,309

### 3D object/plane intersection contour

Hi,
I'd like to compute the intersection between a plane and a 3D object composed of triangles. Then I'd like to draw this intersection contour.

Seemed easy enough at the start. I started by...
8. ## Thread: nVidia - glReadPixels returning garbage sometimes.

by Budric
Replies
6
Views
3,014

### Re: nVidia - glReadPixels returning garbage sometimes.

I think he's referring to the fact that the draw buffer is GL_RGBA and a read of GL_RGB will require a conversion rather than a straight copy.

In the end I need RGB, so someone is going to be...
9. ## Thread: nVidia - glReadPixels returning garbage sometimes.

by Budric
Replies
6
Views
3,014

### Re: nVidia - glReadPixels returning garbage sometimes.

I believe I have found the problem - as far as being able to replicate it on demand.

The images come back as garbage whenever I establish or quit a connection to the machine running the OpenGL...
10. ## Thread: nVidia - glReadPixels returning garbage sometimes.

by Budric
Replies
6
Views
3,014

### Re: nVidia - glReadPixels returning garbage sometimes.

I set GL_PACK_ALIGNMENT when I initialize and create several textures. I don't change it, so it should remain at 1. I will double check with glGet().

The problem is that glReadPixels() returns...
11. ## Thread: nVidia - glReadPixels returning garbage sometimes.

by Budric
Replies
6
Views
3,014

### nVidia - glReadPixels returning garbage sometimes.

I am having an odd problem, occasionally my glReadPixels() from FBO returns garbage. Sometimes it's just mangled pixels, sometimes it's an old image (from rendering before). This happens rarely and...
12. ## Thread: Texture coord to memory coord mapping

by Budric
Replies
3
Views
983

### Re: Texture coord to memory coord mapping

Thanks a lot for your answer. Just to clarify did you mean:
ONE * 3/4 + 0.5/4
Or am I not getting why you're using 3/4 * 3/4 + 0.5/4?
13. ## Thread: fatal error C1189: #error : gl.h included before

by Budric
Replies
3
Views
7,139

### Re: fatal error C1189: #error : gl.h included before

If you are using Visual Studio you can use /showIncludes
http://msdn.microsoft.com/en-us/library/hdkef6tk%28v=VS.100%29.aspx
to track down which file is including gl.h
14. ## Thread: Texture coord to memory coord mapping

by Budric
Replies
3
Views
983

### Texture coord to memory coord mapping

Hi,
I hope someone can clarify some of these concepts. Does OpenGL define texture coordinate (0,0) at the center or the edge of the pixel?

In other words suppose I have a texture that's 4x4...
15. ## Thread: reading the pixels from the image

by Budric
Replies
4
Views
1,330

### Re: reading the pixels from the image

One thing I found when using glReadPixels() is that it's MUCH slower when reading non power of 2 sizes. Try to see if your code gets faster if you read 512x512. This is actually...
16. ## Thread: Efficiency problem with OBJ loader

by Budric
Replies
5
Views
1,742

### Re: Efficiency problem with OBJ loader

You can try using display lists. Google for a tutorial, or here's one: http://www.lighthouse3d.com/opengl/displaylists/

by Budric
Replies
7
Views
3,847

### Re: PBO and texture loading/swapping speed

Thanks Bruce. I will try that application out.

by Budric
Replies
7
Views
3,847

### Re: PBO and texture loading/swapping speed

I'm developing on ATI Radeon 2400 Pro with 256M of VRAM. Each texture is 512x512x512 16 bit so 256 MB (unsigned short computer memory), internal storage when calling glTexImage3D is GL_LUMINANCE12...

by Budric
Replies
7
Views
3,847

### Re: PBO and texture loading/swapping speed

Thanks your example makes sense. Basically it's a volume renderer. You can load several volumes, turn on one or several at a time. The case of 2 being swapped is a simplified case I used to track...
20. ## Thread: glTexImage3D() usage

by Budric
Replies
4
Views
1,587

### Re: glTexImage3D() usage

You can use GL_FLOAT in which case no manipulation is done on the data. Or you can scale your data so that when the driver re-scales it, it's in the correct range.

*Edit*
Actually I'm not...

by Budric
Replies
7
Views
3,847

Hi,
this is another PBO question. PBOs are often suggested to improve texture loading speed. I'm having trouble understanding how exactly they help.

Currently I have a problem of 2 3D textures...
22. ## Thread: glTexImage3D() usage

by Budric
Replies
4
Views
1,587

### Re: glTexImage3D() usage

You should know that internally OpenGL stores all textures as floating point [0..1] for unsigned input and [-1,1] for signed input. The input data you pass it is transformed using equations on page...
23. ## Thread: Window coordinates - simple question

by Budric
Replies
1
Views
1,032

### Re: Window coordinates - simple question

You can't get 3D coordinates from 2D coordinates because the projection loses information. However if you have the depth as well then you can use:
24. ## Thread: Parametric equations and Cartesian coordinates

by Budric
Replies
1
Views
4,383

### Re: Parametric equations and Cartesian coordinates

I don't think you fully understand how to draw a circle. When you have it in parametric form
x=r* cos t
y=r *sin t
You simply iterate t from 0 to 2pi and draw the x,y coordinates that you get for...
25. ## Thread: glDrawPixels() with Alpha Channel

by Budric
Replies
5
Views
2,875

### Re: glDrawPixels() with Alpha Channel

The documentation says there is GL_RGBA. So you'll have change your format in memory from ARGB.

http://www.opengl.org/documentation/specs/man_pages/hardcopy/GL/html/gl/drawpixels.html
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