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