Rotating Shader Help

[reepblue]

Tonight I've been looking for a way to rotate a texture 360 degrees from the center so I can use it on a model sheet. I've only found ex_texcoords0 which pans the texture on the face, but I can't seem to find any values or clues on how I would rotate the texture on the face. Any pointers in the right direction would be appreciated.

[shadmar]

You can apply a 2x2 rotation matrix to the texcoords, something like this would rotate the texture :

 

		    float sinx = sin ( 0.0001 * currenttime );
	    float cosx = cos ( 0.0001 * currenttime );
	    float siny = sin ( 0.0001 * currenttime );
           mat2 rotmatrix =  mat2( cosx, -sinx, siny, cosx);
           vec2 rotuv = rotmatrix*ex_texcoords0;

 

Then use rotuv instead of ex_texcoords0 when you lookup the texture.

[shadmar]

if you just need a fast 90 degree or 180 rotation, you can switch ex_texoords0.xy with yx and -xy -yx etc..

[reepblue]

Thanks, now I just need to figure out how to make it spin from the center for the plane/texture than the front corner. I kind of want to do a spinning animation on my cubes in Vectronic.

 

Edit: No luck so far, I just keep getting effects that reminds me of the Giygas boss battle from EarthBound. I guess I still need help.

[shadmar]

Ah center rotation, just subtract 0.5 from coordinates, rotate and add 0.5.

[shadmar]

Like this :

 

 //find center
vec2 uv = (ex_texcoords0-0.5);

//rotate
float sinx = sin ( 0.001 * currenttime );
float cosx = cos ( 0.001 * currenttime );
float siny = sin ( 0.001 * currenttime );
mat2 rotmatrix = mat2( cosx, -sinx, siny, cosx);

//apply matrix and restore uv (0.5)
vec2 rotuv = rotmatrix*uv+0.5;

//fetch texture using new uv coordinates
outcolor *= texture(texture0,rotuv);

[Roland]

How cool. This will suit my 'Click-To-Go' marker perfectly. Was just wondering how to solve that and here is a solution like sent from heaven.

[reepblue]

Shadmar, you're a hero. Just a tip, make sure that the texture file is Clamped to X and Y to remove the duplicate textures you see in the corners while it's rotating. Now to test my idea with this. Thanks again.