OpenGL third person camera using quaternions

Asked May 12 '18 at 17:31

Active May 13 '18 at 05:11

Viewed 424 times

I'm trying to implement a third person camera in OpenGL. I'm able to get it to work without any problem using euler angles and basic trigonometry:

float cameraDistance = 10.0f;
float cameraPositionX = sin(targetRotation.y) * cameraDistance;
float cameraPositionY = cos(targetRotation.y) * cameraDistance;

ViewMatrix = glm::lookAt(
    glm::vec3(cameraPositionX, cameraPositionY, 30.0f) + targetLocation,
    targetLocation,
    glm::vec3(0,1,0)
);

The problem is when I start to use quaternion to store the target rotations. Converting quaternion to euler angles gives ambiguous results and the above code doesn't work well anymore. For example after crossing 90 degrees, y rotation starts from 0 again but x and z are flipped, so I guess I would need to include x and z in the trigonometry equations as well, but my brain is to tiny figure them out. Is there any way to translate the above code to work with quaternions properly ?

edited May 13 '18 at 05:11

genpfault

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asked May 12 '18 at 17:31

Stefano De La Burczymuchito

2

Why would you use quaternions (plural) to "store the target rotations"? You only need a single quaternion. And you should *never* convert quaternions to euler angles. – Nicol Bolas May 12 '18 at 17:35
Thanks, but I already know that. I'm trying to figure out how to achieve same result but using quaternion instead of euler angles. Basically how to calculate camera x and y using quaternion. – Stefano De La Burczymuchito May 12 '18 at 17:49
2

And I'm saying that you shouldn't be computing those things. You should use the quaternion to generate your view matrix *directly*, not by using `lookAt`. – Nicol Bolas May 12 '18 at 18:17
Ok, now I got it. Thanks ! – Stefano De La Burczymuchito May 12 '18 at 19:45

OpenGL third person camera using quaternions

0 Answers0