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OpenGL, is it useful?

Name: Anonymous 2011-01-30 23:05

I'm a class on OpenGL.  It's the only programming course on graphics I've ever taken.  How many companies actually use openGL to create software?  I've heard of OpenGL before this course, but it seems to me that DirectX is much more popular.  Is what I'm learning applicable to DirectX?

Name: Anonymous 2011-01-30 23:05

*I'm in a class

Name: Anonymous 2011-01-30 23:21

check if they are teaching in immediate mode. drop the class if it is true.

Name: Anonymous 2011-01-30 23:26

yeah, I think we are learning immediate mode.  That's when every frame has to be re-drawn regardless of changes right?  I can't drop it, this is my last term, and if I drop it I'll have to take another term.  Thanks for the input though.  Is immediate mode never used in real-life?

Name: Anonymous 2011-01-30 23:34

>>4
You'll find it useful to know that immediate mode is considered harmful.
http://eddieringle.com/ditching-immediate-mode-opengl-vertex-arrays/

Name: Anonymous 2011-01-30 23:36

nah, it is like
glBegin(...);
glVertex(...);
glVertex(...);
glVertex(...);
...
glEnd();
you pass vertices/normals etc like this which is way too slow for more than like maybe a thousand triangles.

probably they won't even teach about shaders, you should focus on that.

Name: Anonymous 2011-01-30 23:39

>>5
opengl has something like vertex/index buffers and a similar language to hlsl right? If this is true I don't think they are that different other than syntax.

Name: Anonymous 2011-01-30 23:42

>>5

Thanks for the info, and yes, I can now confirm we are using immediate mode.

I've read a little about VBOs, are they better "form" or more efficient than vertex arrays?

Name: Anonymous 2011-01-30 23:54

I would drop the course if I were. It is a start but it really won't help you much. Using a web tutorial would be much useful.

If you can't drop it keep that in the mind all you learn about opengl is wrong. I learned direct3d on my own after learning opengl in school and it made me rage how slow opengl was. but of course this is not opengl's fault, it was the course.

Name: UMH memesmith !gNlkr4vCuc 2011-01-30 23:55

>>8
The main drawback of vertex arrays is that they have to be uploaded to the graphics card every time you draw them. This is a slow operation.

Using VBOs allows you to store the entire vertex array on the graphics card, so you only have to re-send it if it changes.

Ideally you'll also have access to vertex shaders, which will let you move some of your mesh manipulation code to the GPU. That's a different topic though.

Name: !ldNK/hndS6 2011-01-30 23:57

Name: Anonymous 2011-01-31 12:47

whats the best windowing toolkit to back up OpenGL? GLUT? QT?

Name: Anonymous 2011-01-31 14:04

>>12
wat?

Name: Anonymous 2011-01-31 15:35

>>13
OpenGL is just graphics, it doesnt create any windows or any other platform gui widgets. So I just want to know what gui toolkit is good to use with OpenGL

Name: Anonymous 2011-01-31 15:51

>>14
SDL+ OpenGl seems to be a popular option.

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