// Rolls — generated from https://github.com/gl-transitions/gl-transitions/blob/master/transitions/Rolls.glsl
// Author: Mark Craig
// License: MIT
// Description: The outgoing image rolls away around a corner, revealing the incoming one

uniform shader _from;
uniform shader _to;
uniform float2 _resolution;
uniform float progress;
uniform float ratio;

vec4 getFromColor(vec2 uv) { return vec4(unpremul(_from.eval(vec2(uv.x, 1.0 - uv.y) * _resolution))); }
vec4 getToColor(vec2 uv) { return vec4(unpremul(_to.eval(vec2(uv.x, 1.0 - uv.y) * _resolution))); }

uniform int type; 

uniform int RotDown; 

vec4 transition(vec2 uv)
{
float theta, c1, s1;
vec2 iResolution = vec2(ratio, 1.0);
vec2 uvi;

if (type == 0) { theta = ((RotDown != 0) ? 3.14159265358979323846 : -3.14159265358979323846) / 2.0 * progress; uvi.x = 1.0 - uv.x; uvi.y = uv.y; }
else if (type == 1) { theta = ((RotDown != 0) ? 3.14159265358979323846 : -3.14159265358979323846) / 2.0 * progress; uvi = uv; }
else if (type == 2) { theta = ((RotDown != 0) ? -3.14159265358979323846 : 3.14159265358979323846) / 2.0 * progress; uvi.x = uv.x; uvi.y = 1.0 - uv.y; }
else if (type == 3) { theta = ((RotDown != 0) ? -3.14159265358979323846 : 3.14159265358979323846) / 2.0 * progress; uvi = 1.0 - uv; }
c1 = cos(theta); s1 = sin(theta);
vec2 uv2;
uv2.x = (uvi.x * iResolution.x * c1 - uvi.y * iResolution.y * s1);
uv2.y = (uvi.x * iResolution.x * s1 + uvi.y * iResolution.y * c1);
if ((uv2.x >= 0.0) && (uv2.x <= iResolution.x) && (uv2.y >= 0.0) && (uv2.y <= iResolution.y))
	{
	uv2 /= iResolution;
	if (type == 0) { uv2.x = 1.0 - uv2.x; }
	else if (type == 2) { uv2.y = 1.0 - uv2.y; }
	else if (type == 3) { uv2 = 1.0 - uv2; }
	return(getFromColor(uv2));
	}
return(getToColor(uv));
}

half4 main(float2 _coord) {
  vec2 _uv = _coord / _resolution;
  vec4 _c = clamp(transition(vec2(_uv.x, 1.0 - _uv.y)), 0.0, 1.0);
  return half4(_c.rgb * _c.a, _c.a);
}