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/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
#version 120
#define M_PI 3.1415926535897932384626433832795
uniform float time;
uniform ivec2 numTiles;
uniform sampler2D permTexture;
attribute float tileInfo;
varying vec2 v_texturePosition;
varying float v_textureSelect;
float snoise(vec2 p)
{
return texture2D(permTexture, p).r;
}
mat4 rotationMatrix(vec3 axis, float angle)
{
axis = normalize(axis);
float s = sin(angle);
float c = cos(angle);
float oc = 1.0 - c;
return mat4(oc * axis.x * axis.x + c, oc * axis.x * axis.y - axis.z * s, oc * axis.z * axis.x + axis.y * s, 0.0,
oc * axis.x * axis.y + axis.z * s, oc * axis.y * axis.y + c, oc * axis.y * axis.z - axis.x * s, 0.0,
oc * axis.z * axis.x - axis.y * s, oc * axis.y * axis.z + axis.x * s, oc * axis.z * axis.z + c, 0.0,
0.0, 0.0, 0.0, 1.0);
}
void main( void )
{
vec4 v = gl_Vertex;
// Not sure it this is like what it should eventually be; just
// experimenting to get at least something.
// Move the tile on a semicircular path so that it will end up at
// the correct place. All tiles move the same direction around the
// vertical centre axis.
// Each tile moves during only half of the transition. The letmost
// tiles start moving at the start and arrive at their end
// position around time=0.5, when the tiles there (the rightmost
// ones) start moving. (The exact time each tile is moving is
// fuzzed a bit to make a more random appearance.)
// In GLSL 1.20 we don't have any bitwise operators, sigh
int tileXIndex = int(mod(int(tileInfo), 256));
int tileYIndex = int(mod(int(tileInfo) / 256, 256));
int vertexIndexInTile = int(mod(int(tileInfo) / (256*256), 256));
// A semi-random number 0..1, different for neighbouring tiles.
float fuzz = snoise(vec2(float(tileXIndex)/(numTiles.x-1), float(tileYIndex)/(numTiles.y-1)));
// Semi-random rotation direction, identical for tiles that rotate into each other's location
// so that they don't pass through each others in flight, which looks ugly.
float direction = (snoise(vec2(floor(abs(float(numTiles.x-1)/2-tileXIndex))/(float(numTiles.x-1)/2), float(tileYIndex)/(numTiles.y-1))) < 0.5 ? -1 : 1);
float startTime = float(tileXIndex)/(numTiles.x-1) * 0.5 + fuzz*0.2;
float endTime = min(startTime + 0.5, 1.0);
const float ALMOST_ONE = 0.999;
if (time <= startTime)
{
// Still at start location, nothing needed
v_textureSelect = 0;
}
else if (time > startTime && time <= endTime)
{
// Moving
float rotation = direction * (time - startTime) / (endTime - startTime);
// Avoid z fighting
v = rotationMatrix(vec3(0, 1, 0), max(min(rotation, ALMOST_ONE), -ALMOST_ONE)*M_PI) * v;
v_textureSelect = float(rotation > 0.5 || rotation < -0.5);
}
else
{
// At end location. Tile is 180 degrees rotated
// Avoid z fighting
v = rotationMatrix(vec3(0, 1, 0), direction*ALMOST_ONE*M_PI) * v;
v_textureSelect = 1;
}
gl_Position = gl_ModelViewProjectionMatrix * v;
v_texturePosition = gl_MultiTexCoord0.xy;
}
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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