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@donhenton
Last active April 16, 2023 18:06
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Save donhenton/f4c1d6d4de5e0f3bae8ad79eeb04e737 to your computer and use it in GitHub Desktop.
OSL shader for spiral rotating an image
/*
Open shading Language shader that will take an image on a quad (eg blender) and rotate the image in a spiral that
is centered on the quad.
INPUT: in_UVs In Blender the script tag receives a UV input from a texture coordinate node
angle: the angle to rotate, can be animated in blender
OUTPUT: out_UVs modified UVs
*/
shader UV_rotate(
point in_UVs = point(u, v, 0)
[[string label = "UVs In"]] ,
float angle = 359.0
[[string label = "Angle"]] ,
output point out_UVs = 0
[[string label = "UVs out"]]
)
{
// adjust the uvs to center
out_UVs = point(in_UVs[0]-0.5,in_UVs[1]-0.5 ,0.0);
vector axis0 = point(-0.0,-0.0,0);
vector axis1 = point(-0.0,-0.0,1);
// compute the distance from the center
float d = distance(out_UVs ,point(0,0,0));
// further out more rotation
float Angrmp = (angle*(d));
float rads = radians(Angrmp);
point UVoffset = rotate(out_UVs, rads, axis0, axis1);
// return the uvs to the corner
UVoffset = point(UVoffset[0]+0.5,UVoffset[1]+0.5 ,0.0);
out_UVs = UVoffset;
}
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