GLSL.io Transition (v1)

PageCurl.glsl

#ifdef GL_ES
precision highp float;
#endif
uniform sampler2D from, to;
uniform float progress;
uniform vec2 resolution;

// Adapted by Sergey Kosarevsky from:
// http://rectalogic.github.io/webvfx/examples_2transition-shader-pagecurl_8html-example.html

/*
Copyright (c) 2010 Hewlett-Packard Development Company, L.P. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

   * Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above
     copyright notice, this list of conditions and the following disclaimer
     in the documentation and/or other materials provided with the
     distribution.
   * Neither the name of Hewlett-Packard nor the names of its
     contributors may be used to endorse or promote products derived from
     this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
in vec2 texCoord;
*/

const float MIN_AMOUNT = -0.16;
const float MAX_AMOUNT = 1.3;
float amount = progress * (MAX_AMOUNT - MIN_AMOUNT) + MIN_AMOUNT;

const float PI = 3.141592653589793;

const float scale = 512.0;
const float sharpness = 3.0;

float cylinderCenter = amount;
// 360 degrees * amount
float cylinderAngle = 2.0 * PI * amount;

const float cylinderRadius = 1.0 / PI / 2.0;

vec3 hitPoint(float hitAngle, float yc, vec3 point, mat3 rrotation)
{
	float hitPoint = hitAngle / (2.0 * PI);
	point.y = hitPoint;
	return rrotation * point;
}

vec4 antiAlias(vec4 color1, vec4 color2, float distanc)
{
	distanc *= scale;
	if (distanc < 0.0) return color2;
	if (distanc > 2.0) return color1;
	float dd = pow(1.0 - distanc / 2.0, sharpness);
	return ((color2 - color1) * dd) + color1;
}

float distanceToEdge(vec3 point)
{
	float dx = abs(point.x > 0.5 ? 1.0 - point.x : point.x);
	float dy = abs(point.y > 0.5 ? 1.0 - point.y : point.y);
	if (point.x < 0.0) dx = -point.x;
	if (point.x > 1.0) dx = point.x - 1.0;
	if (point.y < 0.0) dy = -point.y;
	if (point.y > 1.0) dy = point.y - 1.0;
	if ((point.x < 0.0 || point.x > 1.0) && (point.y < 0.0 || point.y > 1.0)) return sqrt(dx * dx + dy * dy);
	return min(dx, dy);
}

vec4 seeThrough(float yc, vec2 p, mat3 rotation, mat3 rrotation)
{
	float hitAngle = PI - (acos(yc / cylinderRadius) - cylinderAngle);
	vec3 point = hitPoint(hitAngle, yc, rotation * vec3(p, 1.0), rrotation);
	if (yc <= 0.0 && (point.x < 0.0 || point.y < 0.0 || point.x > 1.0 || point.y > 1.0))
	{
	  vec2 texCoord = gl_FragCoord.xy / resolution.xy;
		return texture2D(to, texCoord);
	}

	if (yc > 0.0) return texture2D(from, p);

	vec4 color = texture2D(from, point.xy);
	vec4 tcolor = vec4(0.0);

	return antiAlias(color, tcolor, distanceToEdge(point));
}

vec4 seeThroughWithShadow(float yc, vec2 p, vec3 point, mat3 rotation, mat3 rrotation)
{
	float shadow = distanceToEdge(point) * 30.0;
	shadow = (1.0 - shadow) / 3.0;

	if (shadow < 0.0) shadow = 0.0; else shadow *= amount;

	vec4 shadowColor = seeThrough(yc, p, rotation, rrotation);
	shadowColor.r -= shadow;
	shadowColor.g -= shadow;
	shadowColor.b -= shadow;

	return shadowColor;
}

vec4 backside(float yc, vec3 point)
{
	vec4 color = texture2D(from, point.xy);
	float gray = (color.r + color.b + color.g) / 15.0;
	gray += (8.0 / 10.0) * (pow(1.0 - abs(yc / cylinderRadius), 2.0 / 10.0) / 2.0 + (5.0 / 10.0));
	color.rgb = vec3(gray);
	return color;
}

vec4 behindSurface(float yc, vec3 point, mat3 rrotation)
{
	float shado = (1.0 - ((-cylinderRadius - yc) / amount * 7.0)) / 6.0;
	shado *= 1.0 - abs(point.x - 0.5);

	yc = (-cylinderRadius - cylinderRadius - yc);

	float hitAngle = (acos(yc / cylinderRadius) + cylinderAngle) - PI;
	point = hitPoint(hitAngle, yc, point, rrotation);

	if (yc < 0.0 && point.x >= 0.0 && point.y >= 0.0 && point.x <= 1.0 && point.y <= 1.0 && (hitAngle < PI || amount > 0.5))
	{
		shado = 1.0 - (sqrt(pow(point.x - 0.5, 2.0) + pow(point.y - 0.5, 2.0)) / (71.0 / 100.0));
		shado *= pow(-yc / cylinderRadius, 3.0);
		shado *= 0.5;
	}
	else
	{
		shado = 0.0;
	}
	
	vec2 texCoord = gl_FragCoord.xy / resolution.xy;

	return vec4(texture2D(to, texCoord).rgb - shado, 1.0);
}

void main()
{
  vec2 texCoord = gl_FragCoord.xy / resolution.xy;
  
  const float angle = 30.0 * PI / 180.0;
	float c = cos(-angle);
	float s = sin(-angle);

	mat3 rotation = mat3( c, s, 0,
								-s, c, 0,
								0.12, 0.258, 1
								);
	c = cos(angle);
	s = sin(angle);

	mat3 rrotation = mat3(	c, s, 0,
									-s, c, 0,
									0.15, -0.5, 1
								);

	vec3 point = rotation * vec3(texCoord, 1.0);

	float yc = point.y - cylinderCenter;

	if (yc < -cylinderRadius)
	{
		// Behind surface
		gl_FragColor = behindSurface(yc, point, rrotation);
		return;
	}

	if (yc > cylinderRadius)
	{
		// Flat surface
		gl_FragColor = texture2D(from, texCoord);
		return;
	}

	float hitAngle = (acos(yc / cylinderRadius) + cylinderAngle) - PI;

	float hitAngleMod = mod(hitAngle, 2.0 * PI);
	if ((hitAngleMod > PI && amount < 0.5) || (hitAngleMod > PI/2.0 && amount < 0.0))
	{
		gl_FragColor = seeThrough(yc, texCoord, rotation, rrotation);
		return;
	}

	point = hitPoint(hitAngle, yc, point, rrotation);

	if (point.x < 0.0 || point.y < 0.0 || point.x > 1.0 || point.y > 1.0)
	{
		gl_FragColor = seeThroughWithShadow(yc, texCoord, point, rotation, rrotation);
		return;
	}

	vec4 color = backside(yc, point);

	vec4 otherColor;
	if (yc < 0.0)
	{
		float shado = 1.0 - (sqrt(pow(point.x - 0.5, 2.0) + pow(point.y - 0.5, 2.0)) / 0.71);
		shado *= pow(-yc / cylinderRadius, 3.0);
		shado *= 0.5;
		otherColor = vec4(0.0, 0.0, 0.0, shado);
	}
	else
	{
		otherColor = texture2D(from, texCoord);
	}

	color = antiAlias(color, otherColor, cylinderRadius - abs(yc));

	vec4 cl = seeThroughWithShadow(yc, texCoord, point, rotation, rrotation);
	float dist = distanceToEdge(point);

	gl_FragColor = antiAlias(color, cl, dist);
}

uniforms.default.json

{}

~LICENSE

GLSL.io Transition License (v1): 
The MIT License (MIT)

Copyright (C) 2014 contact@glsl.io

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.