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cross-animated.frag
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cross-animated.frag
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// Author @patriciogv ( patriciogonzalezvivo.com ) - 2015
#ifdef GL_ES
precision mediump float;
#endif
#define PI 3.14159265359
uniform vec2 u_resolution;
uniform float u_time;
mat2 rotate2d(float _angle){
return mat2(cos(_angle),-sin(_angle),
sin(_angle),cos(_angle));
}
float box(in vec2 _st, in vec2 _size){
_size = vec2(0.5) - _size*0.5;
vec2 uv = smoothstep(_size,
_size+vec2(0.001),
_st);
uv *= smoothstep(_size,
_size+vec2(0.001),
vec2(1.0)-_st);
return uv.x*uv.y;
}
float cross(in vec2 _st, float _size){
return box(_st, vec2(_size,_size/4.)) +
box(_st, vec2(_size/4.,_size));
}
void main(){
vec2 st = gl_FragCoord.xy/u_resolution.xy;
vec3 color = vec3(0.0);
// move space from the center to the vec2(0.0)
st -= vec2(0.5);
// rotate the space
st = rotate2d( sin(u_time*0.5)*PI ) * st;
// move it back to the original place
st += vec2(0.5);
// To move the cross we move the space
vec2 translate = vec2(cos(u_time),sin(u_time));
st += translate*0.35;
// Show the coordinates of the space on the background
// color = vec3(st.x,st.y,0.0);
// Add the shape on the foreground
color += vec3(cross(st,0.25));
gl_FragColor = vec4(color,1.0);
}