Rotate UV in GLSL

rotate-uv.glsl

vec2 rotateUV(vec2 uv, float rotation)
{
    float mid = 0.5;
    return vec2(
        cos(rotation) * (uv.x - mid) + sin(rotation) * (uv.y - mid) + mid,
        cos(rotation) * (uv.y - mid) - sin(rotation) * (uv.x - mid) + mid
    );
}

vec2 rotateUV(vec2 uv, float rotation, vec2 mid)
{
    return vec2(
      cos(rotation) * (uv.x - mid.x) + sin(rotation) * (uv.y - mid.y) + mid.x,
      cos(rotation) * (uv.y - mid.y) - sin(rotation) * (uv.x - mid.x) + mid.y
    );
}

vec2 rotateUV(vec2 uv, float rotation, float mid)
{
    return vec2(
      cos(rotation) * (uv.x - mid) + sin(rotation) * (uv.y - mid) + mid,
      cos(rotation) * (uv.y - mid) - sin(rotation) * (uv.x - mid) + mid
    );
}

#pragma glslify: export(rotateUV)

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Compute cos()/sin() once.

vec2 rotateUV(vec2 uv, float rotation)
{
    float mid = 0.5;
    float cosAngle = cos(rotation);
    float sinAngle = sin(rotation);
    return vec2(
        cosAngle * (uv.x - mid) + sinAngle * (uv.y - mid) + mid,
        cosAngle * (uv.y - mid) - sinAngle * (uv.x - mid) + mid
    );
}

vec2 rotateUV(vec2 uv, float rotation, vec2 mid)
{
    float cosAngle = cos(rotation);
    float sinAngle = sin(rotation);
    return vec2(
        cosAngle * (uv.x - mid.x) + sinAngle * (uv.y - mid.y) + mid.x,
        cosAngle * (uv.y - mid.y) - sinAngle * (uv.x - mid.x) + mid.y
    );
}

vec2 rotateUV(vec2 uv, float rotation, float mid)
{
    float cosAngle = cos(rotation);
    float sinAngle = sin(rotation);
    return vec2(
        cosAngle * (uv.x - mid) + sinAngle * (uv.y - mid) + mid,
        cosAngle * (uv.y - mid) - sinAngle * (uv.x - mid) + mid
    );
}

Compute point once:

vec2 rotateUV(vec2 uv, float rotation)
{
    float cosAngle = cos(rotation);
    float sinAngle = sin(rotation);
    vec2 p = uv - vec2(0.5);
    return vec2(
        cosAngle * p.x + sinAngle * p.y + 0.5,
        cosAngle * p.y - sinAngle * p.x + 0.5
    );
}

vec2 rotateUV(vec2 uv, float rotation, vec2 mid)
{
    float cosAngle = cos(rotation);
    float sinAngle = sin(rotation);
    vec2 p = uv - mid;
    return vec2(
        cosAngle * p.x + sinAngle * p.y + mid.x,
        cosAngle * p.y - sinAngle * p.x + mid.y
    );
}

vec2 rotateUV(vec2 uv, float rotation, float mid)
{
    float cosAngle = cos(rotation);
    float sinAngle = sin(rotation);
    vec2 p = uv - vec2(mid);
    return vec2(
        cosAngle * p.x + sinAngle * p.y + mid,
        cosAngle * p.y - sinAngle * p.x + mid
    );
}

#pragma glslify: export(rotateUV)

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