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path: root/slideshow/opengl/vortexVertexShader.glsl
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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

attribute vec3 a_position;
attribute vec3 a_normal;
attribute vec2 a_texCoord;

uniform mat4 u_projectionMatrix;
uniform mat4 u_modelViewMatrix;
uniform mat4 u_sceneTransformMatrix;
uniform mat4 u_primitiveTransformMatrix;
uniform mat4 u_operationsTransformMatrix;

varying vec2 v_texturePosition;
varying vec3 v_normal;

uniform float time;
uniform ivec2 numTiles;
uniform sampler2D permTexture;
attribute float tileInfo;
uniform float slide;

varying vec4 debug;

#if __VERSION__ < 140
mat4 inverse(mat4 m)
{
    float a00 = m[0][0], a01 = m[0][1], a02 = m[0][2], a03 = m[0][3];
    float a10 = m[1][0], a11 = m[1][1], a12 = m[1][2], a13 = m[1][3];
    float a20 = m[2][0], a21 = m[2][1], a22 = m[2][2], a23 = m[2][3];
    float a30 = m[3][0], a31 = m[3][1], a32 = m[3][2], a33 = m[3][3];

    float b00 = a00 * a11 - a01 * a10;
    float b01 = a00 * a12 - a02 * a10;
    float b02 = a00 * a13 - a03 * a10;
    float b03 = a01 * a12 - a02 * a11;
    float b04 = a01 * a13 - a03 * a11;
    float b05 = a02 * a13 - a03 * a12;
    float b06 = a20 * a31 - a21 * a30;
    float b07 = a20 * a32 - a22 * a30;
    float b08 = a20 * a33 - a23 * a30;
    float b09 = a21 * a32 - a22 * a31;
    float b10 = a21 * a33 - a23 * a31;
    float b11 = a22 * a33 - a23 * a32;

    float det = b00 * b11 - b01 * b10 + b02 * b09 + b03 * b08 - b04 * b07 + b05 * b06;

    return mat4(
        a11 * b11 - a12 * b10 + a13 * b09,
        a02 * b10 - a01 * b11 - a03 * b09,
        a31 * b05 - a32 * b04 + a33 * b03,
        a22 * b04 - a21 * b05 - a23 * b03,
        a12 * b08 - a10 * b11 - a13 * b07,
        a00 * b11 - a02 * b08 + a03 * b07,
        a32 * b02 - a30 * b05 - a33 * b01,
        a20 * b05 - a22 * b02 + a23 * b01,
        a10 * b10 - a11 * b08 + a13 * b06,
        a01 * b08 - a00 * b10 - a03 * b06,
        a30 * b04 - a31 * b02 + a33 * b00,
        a21 * b02 - a20 * b04 - a23 * b00,
        a11 * b07 - a10 * b09 - a12 * b06,
        a00 * b09 - a01 * b07 + a02 * b06,
        a31 * b01 - a30 * b03 - a32 * b00,
        a20 * b03 - a21 * b01 + a22 * b00) / det;
}
#endif

float snoise(vec2 p)
{
    return texture2D(permTexture, p).r;
}

mat4 identityMatrix(void)
{
    return mat4(1.0, 0.0, 0.0, 0.0,
                0.0, 1.0, 0.0, 0.0,
                0.0, 0.0, 1.0, 0.0,
                0.0, 0.0, 0.0, 1.0);
}

mat4 translationMatrix(vec3 axis)
{
    mat4 matrix = identityMatrix();
    matrix[3] = vec4(axis, 1.0);
    return matrix;
}

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 = vec4(a_position, 1.0);
    vec4 normal = vec4(a_normal, 1.0);

    // 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));

    // A semi-random number 0..1, different for neighbouring tiles, to know when they should start moving.
    float startTimeFuzz = snoise(vec2(float(tileXIndex)/(numTiles.x-1), float(tileYIndex)/(numTiles.y-1)));

    // A semi-random number -1.5..1.5, different for neighbouring tiles, to specify their rotation center.
    // The additional 0.5 on each side is because we want some tiles to rotate outside.
    float rotationFuzz = snoise(vec2(float(numTiles.x + tileXIndex)/(numTiles.x-1), float(tileYIndex)/(numTiles.y-1))) * 3.0 - 1.5;

    float startTime = float(tileXIndex)/(numTiles.x-1) * 0.2 + startTimeFuzz * 0.2;
    float endTime = min(startTime + 0.7, 1.0);

    bool isLeavingSlide = (slide < 0.5);
    const vec4 invalidPosition = vec4(-256.0, -256.0, -256.0, -256.0);

    float nTime;

    // Don’t display the tile before or after its rotation, depending on the slide.
    if (!isLeavingSlide)
    {
        if (time < max(0.3, startTime))
        {
            gl_Position = invalidPosition;
            return;
        }
        nTime = 1.0 - time;
    }
    else
    {
        if (time > endTime)
        {
            gl_Position = invalidPosition;
            return;
        }
        nTime = time;
    }

    mat4 transform = identityMatrix();
    if (nTime > startTime && nTime <= endTime)
    {
        // We are in the rotation part.
        float rotation = -(nTime - startTime) / (endTime - startTime);

        // Translation vector to set the origin of the rotation.
        vec3 translationVector = vec3(rotationFuzz, 0.0, 0.0);

        // Compute the actual rotation matrix.
        transform = translationMatrix(translationVector)
                  * rotationMatrix(vec3(0, 1, 0), clamp(rotation, -1.0, 1.0) * M_PI)
                  * translationMatrix(-translationVector)
                  * transform;

        // Add a translation movement to the leaving slide so it doesn’t exactly mirror the entering one.
        if (isLeavingSlide && nTime > 0.3)
        {
            float movement = smoothstep(0.0, 1.0, (nTime - 0.3) * 2.0);
            transform = translationMatrix(vec3(-movement, 0.0, -0.5 * movement)) * transform;
        }
    }

    // Apply our transform operations.
    v = transform * v;
    normal = transform * normal;

    mat4 modelViewMatrix = u_modelViewMatrix * u_operationsTransformMatrix * u_sceneTransformMatrix * u_primitiveTransformMatrix;
    mat3 normalMatrix = mat3(transpose(inverse(modelViewMatrix)));
    gl_Position = u_projectionMatrix * modelViewMatrix * v;

    v_texturePosition = a_texCoord;
    v_normal = normalize(normalMatrix * vec3(normal));
}

/* vim:set shiftwidth=4 softtabstop=4 expandtab: */