math – rotate uv

Shader port from https://www.shadertoy.com/view/mssSWN

Shader code
shader_type canvas_item;

uniform float scale: hint_range(0.0,1.0) = 1.0;
uniform float time_scale: hint_range(0.0,2.0) = 1.0;


void fragment()
{
    //set the uv to a proper size on the center of screen 
    vec2 uv = (FRAGCOORD.xy - 0.5 * (scale / SCREEN_PIXEL_SIZE.xy)) / min(scale / SCREEN_PIXEL_SIZE.x, scale / SCREEN_PIXEL_SIZE.y);
    // set rotation angle value
    float rot = radians(0.0);
    // this set rotation by time and 
    rot = TIME * time_scale;
    // algebra formula for rotation by matrix , https://en.wikipedia.org/wiki/Rotation_matrix
    mat2 m = mat2( vec2( cos(rot), -sin(rot) ), vec2( sin(rot), cos(rot) ) );
    // rotation of uv with matrix algebra formula where is set the rotation angle 
    uv = m* uv;
    // define float by function module from 1.0 and uv.x - uv.y
    float d = mod(uv.x - uv.y, 1.0);
    // color for fragColor is value of fload d by module function
    vec4 col = vec4(vec3(d), 1.0);
    COLOR = vec4(col);
}
Tags
#shadertoy
The shader code and all code snippets in this post are under CC0 license and can be used freely without the author's permission. Images and videos, and assets depicted in those, do not fall under this license. For more info, see our License terms.

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