Rotation around point other than origin

Game Mechanics
#1

Now that I have my transformations applied to a vertex shader, I realized that no matter what translations have occurred, the rotation is always around the origin. Here is my rotation code (pulled from Matrix4f in lwjgl-util). Any ideas on why this rotation doesn’t rotate round translated coordinate would be appreciated.

// all matrix values are in the same order as Matrix4f.java from lwjgl
public Matrix rotate(float radians, float x, float y, float z) {
		Matrix src = this;
		float c = (float) Math.cos(radians);
		float s = (float) Math.sin(radians);
		float oneminusc = 1.0f - c;
		float xy = x*y;
		float yz = y*z;
		float xz = x*z;
		float xs = x*s;
		float ys = y*s;
		float zs = z*s;
		float f00 = x*x*oneminusc+c;
		float f01 = xy*oneminusc+zs;
		float f02 = xz*oneminusc-ys;
		// n[3] not used
		float f10 = xy*oneminusc-zs;
		float f11 = y*y*oneminusc+c;
		float f12 = yz*oneminusc+xs;
		// n[7] not used
		float f20 = xz*oneminusc+ys;
		float f21 = yz*oneminusc-xs;
		float f22 = z*z*oneminusc+c;
		float t00 = src.m00 * f00 + src.m10 * f01 + src.m20 * f02;
		float t01 = src.m01 * f00 + src.m11 * f01 + src.m21 * f02;
		float t02 = src.m02 * f00 + src.m12 * f01 + src.m22 * f02;
		float t03 = src.m03 * f00 + src.m13 * f01 + src.m23 * f02;
		float t10 = src.m00 * f10 + src.m10 * f11 + src.m20 * f12;
		float t11 = src.m01 * f10 + src.m11 * f11 + src.m21 * f12;
		float t12 = src.m02 * f10 + src.m12 * f11 + src.m22 * f12;
		float t13 = src.m03 * f10 + src.m13 * f11 + src.m23 * f12;
		m20 = src.m00 * f20 + src.m10 * f21 + src.m20 * f22;
		m21 = src.m01 * f20 + src.m11 * f21 + src.m21 * f22;
		m22 = src.m02 * f20 + src.m12 * f21 + src.m22 * f22;
		m23 = src.m03 * f20 + src.m13 * f21 + src.m23 * f22;
		m00 = t00;
		m01 = t01;
		m02 = t02;
		m03 = t03;
		m10 = t10;
		m11 = t11;
		m12 = t12;
		m13 = t13;
		return this;
	}

Any help would be appreciated,
CopyableCougar4

#2

This comes up very often. Translate to the point then rotate then translate back

#3

I am, but it still rotates around the origin.

This is how I rotate:

graphics.translate(new Vector((Application.getApplication().getWidth() / 2), 
				(Application.getApplication().getHeight() / 2), 0));
		graphics.rotate((float) Math.toDegrees(1), new Vector(0, 0, 1));
		graphics.translate(new Vector((Application.getApplication().getWidth() / 2), 
				(Application.getApplication().getHeight() / 2), 0).invert());

This is how i revert after rendering:

graphics.translate(new Vector((Application.getApplication().getWidth() / 2), 
				(Application.getApplication().getHeight() / 2), 0));
		graphics.rotate((float) Math.toDegrees(-1), new Vector(0, 0, 1));
		graphics.translate(new Vector((Application.getApplication().getWidth() / 2), 
				(Application.getApplication().getHeight() / 2), 0).invert());

But it doesn’t rotate around the given point.

#4

I guess the issue is solved? It works not but I don’t really know why.

#5

What do you mean?

#6

Well now the rotation works just fine, but I didn’t change anything except the angle of rotation.

#7

It’s in radians that could be the issue.

#8

This is stated backwards. Translate the center of the rotation to the origin, rotate and then translate back to original: p’ = rot(p-c)+c.