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rejooh

Member Since 02 Apr 2013
Offline Last Active Jun 08 2013 09:07 AM

Topics I've Started

LWJGL ModelViewProjection Camera Rotation

02 April 2013 - 03:15 PM

Hello everyone,
I registered to get some help regarding a question relating camera rotation. Following multiple tutorials (LWJGL-Wiki MVP: http://www.lwjgl.org/wiki/index.php?title=The_Quad_with_Projection,_View_and_Model_matrices & OpenGL-Tutorial.org: http://www.opengl-tutorial.org/beginners-tutorials/tutorial-6-keyboard-and-mouse/) I was able to create some cubes that are rendered with the use of model-, view- and projectionmatrices in Java 7 using LWJGL. Since this morning I am trying to implement camera movement and rotation. Everything seems to work fine, but with a closer look the camera (respectively the world) seems to translate when rotating.
 
Is that behavior normal or is something seriously wrong?
 
The following video shows what I am trying to describe: 
 
Here is the code, that creates the matrices, Projection (with 45f, 1280f / 720f, 0.1f, 100f):
public static Matrix4f projectionMatrix(float fov, float aspect, float near, float far) {
	float frustum = far - near;
	float scaleY = (float)(1f / Math.tan(Math.toRadians(fov / 2f)));
	float scaleX = scaleY / aspect;
		
	Matrix4f result = new Matrix4f();
	result.m00 = scaleX;
	result.m11 = scaleY;
	result.m22 = -((far + near) / frustum);
	result.m23 = -1;
	result.m32 = -((2 * near * far) / frustum);
		
	return result;
}
 
 
View (eye is the cameras position, up is (0f, 1f, 0f):
public static Matrix4f lookAtMatrix(Vector3f eye, Vector3f target, Vector3f up) {
	Vector3f zaxis = new Vector3f(
		target.x - eye.x,
		target.y - eye.y,
		target.z - eye.z
	);
	zaxis.normalise();
		
	Vector3f xaxis = new Vector3f();
	Vector3f.cross(up, zaxis, xaxis);
	xaxis.normalise();
		
	Vector3f yaxis = new Vector3f();
	Vector3f.cross(zaxis, xaxis, yaxis);
		
	Matrix4f rotation = new Matrix4f();
	rotation.m00 = xaxis.x;
	rotation.m01 = yaxis.x;
	rotation.m02 = zaxis.x;
	rotation.m10 = xaxis.y;
	rotation.m11 = yaxis.y;
	rotation.m12 = zaxis.y;
	rotation.m20 = xaxis.z;
	rotation.m21 = yaxis.z;
	rotation.m22 = zaxis.z;		
	rotation.m33 = 1;
		
	Matrix4f translation = new Matrix4f();
	translation.m00 = 1;
	translation.m11 = 1;
	translation.m22 = 1;
	translation.m30 = -eye.x;
	translation.m31 = -eye.y;
	translation.m32 = -eye.z;
	translation.m33 = 1;
		
	Matrix4f result = new Matrix4f();
	Matrix4f.mul(rotation, translation, result);
	
	return result;
}
 
I calculate the target with the following code (position, yaw and pitch are attributes of the camera):
Vector3f target = new Vector3f(
	position.x - (float) (Math.cos(Math.toRadians(pitch)) * Math.sin(Math.toRadians(yaw))),
	position.y + (float) (Math.sin(Math.toRadians(pitch))),
	position.z + (float) (Math.cos(Math.toRadians(pitch)) * Math.cos(Math.toRadians(yaw)))
);
 
The model matrices shouldn't be the problem.
 
The vertex shader calculates the MVP (but also shouldn't be the problem):
#version 330 core

uniform mat4 projectionMatrix;
uniform mat4 viewMatrix;
uniform mat4 modelMatrix;

in vec4 in_Position;
in vec4 in_Color;

out vec4 pass_Color;

void main(void) {
	gl_Position = projectionMatrix * viewMatrix * modelMatrix  * in_Position;
	pass_Color = in_Color;
}
 
 
Hope, someone is able to help me.
Thanks, rejooh.

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