/****************************************************************************
**
** Copyright (C) 2014 Klaralvdalens Datakonsult AB (KDAB).
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt3D module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "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 The Qt Company Ltd 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."
**
** $QT_END_LICENSE$
**
****************************************************************************/

attribute vec3 vertexPosition;
attribute vec3 vertexNormal;
attribute vec2 vertexTexCoord;
attribute vec4 vertexTangent;

varying vec4 positionInLightSpace;
varying vec3 lightDir;
varying vec3 viewDir;
varying vec2 texCoord;

uniform mat4 viewMatrix;
uniform mat4 lightViewProjection;
uniform mat4 modelMatrix;
uniform mat4 modelView;
uniform mat3 modelViewNormal;
uniform mat4 mvp;

uniform float texCoordScale;

uniform vec3 lightPosition;

void main()
{
    const mat4 shadowMatrix = mat4(0.5, 0.0, 0.0, 0.0,
                                   0.0, 0.5, 0.0, 0.0,
                                   0.0, 0.0, 0.5, 0.0,
                                   0.5, 0.5, 0.5, 1.0);

    positionInLightSpace = shadowMatrix * lightViewProjection * modelMatrix * vec4(vertexPosition, 1.0);

    // Pass through texture coordinates
    texCoord = vertexTexCoord * texCoordScale;

    // Transform position, normal, and tangent to eye coords
    vec3 normal = normalize(modelViewNormal * vertexNormal);
    vec3 tangent = normalize(modelViewNormal * vertexTangent.xyz);
    vec3 position = vec3(modelView * vec4(vertexPosition, 1.0));

    // Calculate binormal vector
    vec3 binormal = normalize(cross(normal, tangent));

    // Construct matrix to transform from eye coords to tangent space
    mat3 tangentMatrix = mat3 (
        tangent.x, binormal.x, normal.x,
        tangent.y, binormal.y, normal.y,
        tangent.z, binormal.z, normal.z);

    // Transform light direction and view direction to tangent space
    vec3 s = lightPosition - position;
    lightDir = normalize(tangentMatrix * vec3(viewMatrix * vec4(s, 1.0)));

    vec3 v = -position;
    viewDir = normalize(tangentMatrix * v);

    // Calculate vertex position in clip coordinates
    gl_Position = mvp * vec4(vertexPosition, 1.0);
}