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/*
* Copyright (c)2012 Adobe Systems Incorporated. All rights reserved.
* Copyright (c)2012 Branislav Ulicny
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
precision mediump float;
// Built-in attributes
attribute vec4 a_position;
attribute vec2 a_texCoord;
attribute vec3 a_triangleCoord;
// Built-in uniforms
uniform mat4 u_projectionMatrix;
uniform vec2 u_meshSize;
uniform vec2 u_textureSize;
// Uniform passed in from CSS
uniform mat4 transform;
uniform float amount;
uniform float randomness;
uniform vec3 flipAxis;
// Varyings
varying float v_depth;
varying vec2 v_uv;
// Constants
const float PI2 = 1.5707963267948966;
// Create perspective matrix
mat4 perspectiveMatrix(float p)
{
float perspective = - 1.0 / p;
return mat4(
1.0, 0.0, 0.0, 0.0,
0.0, 1.0, 0.0, 0.0,
0.0, 0.0, 1.0, perspective,
0.0, 0.0, 0.0, 1.0
);
}
// Rotate vector
vec3 rotateVectorByQuaternion(vec3 v, vec4 q)
{
vec3 dest = vec3(0.0);
float x = v.x, y = v.y, z = v.z;
float qx = q.x, qy = q.y, qz = q.z, qw = q.w;
// Calculate quaternion * vector.
float ix = qw * x + qy * z - qz * y,
iy = qw * y + qz * x - qx * z,
iz = qw * z + qx * y - qy * x,
iw = -qx * x - qy * y - qz * z;
// Calculate result * inverse quaternion.
dest.x = ix * qw + iw * -qx + iy * -qz - iz * -qy;
dest.y = iy * qw + iw * -qy + iz * -qx - ix * -qz;
dest.z = iz * qw + iw * -qz + ix * -qy - iy * -qx;
return dest;
}
// Convert rotation.
vec4 axisAngleToQuaternion(vec3 axis, float angle)
{
vec4 dest = vec4(0.0);
float halfAngle = angle / 2.0;
float s = sin(halfAngle);
dest.x = axis.x * s;
dest.y = axis.y * s;
dest.z = axis.z * s;
dest.w = cos(halfAngle);
return dest;
}
// Random function based on the tile coordinate.
// This will return the same value for all the vertices in the same tile (i.e. two triangles).
float random(vec2 scale)
{
// Use the fragment position as a different seed per-pixel.
return fract(sin(dot(vec2(a_triangleCoord.x, a_triangleCoord.y), scale)) * 4000.0);
}
// Main
void main()
{
// FIXME: We must swap x and y as a workaround for:
// https://bugs.webkit.org/show_bug.cgi?id=96285
vec2 u_meshSize = u_meshSize.yx;
vec4 pos = a_position;
float aspect = u_textureSize.x / u_textureSize.y;
float cx = a_triangleCoord.x / u_meshSize.y - 0.5 + 0.5 / u_meshSize.y;
float cy = a_triangleCoord.y / u_meshSize.x - 0.5 + 0.5 / u_meshSize.x;
vec3 centroid = vec3(cx, cy, 0.0);
float r = random(vec2(10.0, 80.0));
float rr = mix(0.0, PI2, amount * (1.0 + randomness * r));
vec4 rotation = vec4(flipAxis, rr);
vec4 qRotation = axisAngleToQuaternion(normalize(rotation.xyz), rotation.w);
vec3 newPosition = rotateVectorByQuaternion((pos.xyz - centroid)* vec3(aspect, 1., 1.0), qRotation) * vec3(1.0 / aspect, 1.0, 1.0) + centroid;
pos.xyz = newPosition;
gl_Position = u_projectionMatrix * transform * pos;
// Pass varyings to the fragment shader.
v_depth = abs(rr)/ PI2;
v_uv = a_texCoord;
}
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