Comments on: 23. OpenGL Camera Part 2

By: Swiftless

Swiftless — Mon, 23 May 2011 02:05:25 +0000

Hi drew,

That’s a problem with how WordPress converts the characters.

Cheers,
Swiftless

By: drew

drew — Sun, 22 May 2011 17:52:29 +0000

In Code::Blocks, you need to replace the single quotation marks. But good overall code!!!

By: Glut Camera/stray error: need tutorial/advice

Glut Camera/stray error: need tutorial/advice — Sun, 22 May 2011 00:22:09 +0000

[...] 23 Code is adapted from: 23. OpenGL Camera Part 2 | Swiftless Tutorials [...]

By: Swiftless

Swiftless — Fri, 20 May 2011 02:19:35 +0000

Hi Joshua,

It doesn’t technically have gimbal lock when you first start, it can however suffer from gimbal lock. This is only a starter, as we don’t want to scare people away with quaternions straight away.

Cheers,
Swiftless

By: Joshua

Joshua — Mon, 16 May 2011 20:20:13 +0000

This implementation has gimbal lock

By: Simple OpenGL Keyboard and Mouse FPS Controls | r3dux.org

Simple OpenGL Keyboard and Mouse FPS Controls | r3dux.org — Fri, 13 May 2011 00:19:08 +0000

[...] SuperBible and did some googling, where I came across Swiftless‘ camera tutorials (Part 1, Part 2, Part 3) which gave me a really good start (Thank you, Swiftless!) on how to manipulate the [...]

By: Swiftless

Swiftless — Thu, 21 Apr 2011 00:58:02 +0000

Hi Enrico,

That’s definitely true about math.h and M_PI!

As for saying what I’m doing is incorrect, I hate to disappoint, but there is absolutely nothing wrong with it. In fact, it is a lot riskier to mess around with your GL_PROJECTION matrix and debugging your camera code can be a massive pain. The GL_PROJECTION matrix defines the projection from 3D to 2D on our screen, not where we are in our 3D scene.

As a camera moves around a 3D scene, it makes a lot more sense to move the objects around the point of projection, to me that makes more sense anyway.

I recommend you take a look at the following article on GL_PROJECTION abuse:
http://www.sjbaker.org/steve/omniv/projection_abuse.html

Cheers,
Swiftless

By: Enrico

Enrico — Wed, 20 Apr 2011 09:56:47 +0000

Hi, two suggestions:

- if you include math.h you can use the M_PI define for the pi angle.
- you are moving the modelview around, it’s incorrect, you want to move the camera, so in the display you should traslate and rotate the GL_PROJECTION, and then before the return point, set the GL_MODELVIEW again. Obviously, if you do this you have to change all the functions, but it’s the correct way.

Anyway very good tutorial keep up the good work!

By: Grugi

Grugi — Sat, 09 Apr 2011 21:00:54 +0000

Really good. It helped me a lot. I’m working OpenGL with SDL instead GLUT, but that strafe movement was what I wanted to learn how to implement.
I was using gluLookAt() to try to do that, but I understood the way you did. Thanks!

By: Jake

Jake — Sun, 20 Jun 2010 21:10:30 +0000

Hello,

I am working on a project that involves being able to walk around a scene using the asdw keys and looking around using the arrow keys. I just recently added lighting effects to the mix. I also have a variable ‘mode’ that determines whether the scene is viewed in orthogonal mode or perspective mode. In orthogonal mode, I not able to change the position of the camera or eye (however you wanna think of it). You can only walk around in the perspective mode. When in orthogonal mode, the lighting effects work. But as soon as I switch to perspective mode, it is as if I never applied the lighting effects. The global ambiance is back and light intensities do not change. Would you have any insight as to why this would be happening. I was wondering if it had anything to do with the specific method you used to create the first person perspective as opposed to using something like gluLookAt(). Thanks