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adriancmiranda/glsl-rotation-2d

Forked from yiwenl/glsl-rotation-2d
Last active February 27, 2020 19:09
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glsl-rotation-2d
vec2 rotate(vec2 v, float a) {
float s = sin(a);
float c = cos(a);
mat2 m = mat2(c, -s, s, c);
return m * v;
}
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glsl-rotation-3d
mat4 rotationMatrix(vec3 axis, float angle) {
axis = normalize(axis);
float s = sin(angle);
float c = cos(angle);
float oc = 1.0 - c;
return mat4(
oc * axis.x * axis.x + c, oc * axis.x * axis.y - axis.z * s, oc * axis.z * axis.x + axis.y * s, 0.0,
oc * axis.x * axis.y + axis.z * s, oc * axis.y * axis.y + c, oc * axis.y * axis.z - axis.x * s, 0.0,
oc * axis.z * axis.x - axis.y * s, oc * axis.y * axis.z + axis.x * s, oc * axis.z * axis.z + c, 0.0,
0.0, 0.0, 0.0, 1.0
);
}
vec3 rotate3d(vec3 v, vec3 axis, float angle) {
mat4 m = rotationMatrix(axis, angle);
return (m * vec4(v, 1.0)).xyz;
}
@adriancmiranda
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vec2 rotate2d(vec2 v, float a) {
	float s = sin(a);
	float c = cos(a);
	mat2 m = mat2(c, -s, s, c);
	return m * v;
}

mat4 rotationMatrix(vec3 axis, float angle) {
	axis = normalize(axis);
	float s = sin(angle);
	float c = cos(angle);
	float oc = 1.0 - c;
	return mat4(
		oc * axis.x * axis.x + c,
		oc * axis.x * axis.y - axis.z * s,
		oc * axis.z * axis.x + axis.y * s,
		0.0,
		oc * axis.x * axis.y + axis.z * s,
		oc * axis.y * axis.y + c,
		oc * axis.y * axis.z - axis.x * s,
		0.0,
		oc * axis.z * axis.x - axis.y * s,
		oc * axis.y * axis.z + axis.x * s,
		oc * axis.z * axis.z + c,
		0.0,
		0.0,
		0.0,
		0.0,
		1.0
	);
}

vec3 rotate3d(vec3 v, vec3 axis, float angle) {
	mat4 m = rotationMatrix(axis, angle);
	return (m * vec4(v, 1.0)).xyz;
}

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