Add ES3-specific coordinate systems shader fragment

Change-Id: Ie7f469278b0a74b4c059ad99ad182059c6752cd8
Reviewed-by: Mike Krus <mike.krus@kdab.com>

2 files changed, 74 insertions, 0 deletions

diff --git a/src/extras/extras.qrc b/src/extras/extras.qrc
index 8bbffd272..2aedc6622 100644
--- a/src/extras/extras.qrc
+++ b/src/extras/extras.qrc
@@ -13,6 +13,7 @@
         <file>shaders/es3/metalrough.inc.frag</file>
         <file>shaders/gl3/coordinatesystems.inc</file>
         <file>shaders/es2/coordinatesystems.inc</file>
+        <file>shaders/es3/coordinatesystems.inc</file>
         <file>shaders/gl3/default.vert</file>
         <file>shaders/es2/default.vert</file>
         <file>shaders/es3/default.vert</file>
diff --git a/src/extras/shaders/es3/coordinatesystems.inc b/src/extras/shaders/es3/coordinatesystems.inc
new file mode 100644
index 000000000..9c0f99ddd
--- /dev/null
+++ b/src/extras/shaders/es3/coordinatesystems.inc
@@ -0,0 +1,73 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 Klaralvdalens Datakonsult AB (KDAB).
+** 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."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef FP
+#define FP highp
+#endif
+
+FP mat3 calcWorldSpaceToTangentSpaceMatrix(const in FP vec3 wNormal, const in FP vec4 wTangent)
+{
+    // Make the tangent truly orthogonal to the normal by using Gram-Schmidt.
+    // This allows to build the tangentMatrix below by simply transposing the
+    // tangent -> eyespace matrix (which would now be orthogonal)
+    FP vec3 wFixedTangent = normalize(wTangent.xyz - dot(wTangent.xyz, wNormal) * wNormal);
+
+    // Calculate binormal vector. No "real" need to renormalize it,
+    // as built by crossing two normal vectors.
+    // To orient the binormal correctly, use the fourth coordinate of the tangent,
+    // which is +1 for a right hand system, and -1 for a left hand system.
+    FP vec3 wBinormal = cross(wNormal, wFixedTangent.xyz) * wTangent.w;
+
+    // Construct matrix to transform from world space to tangent space
+    // This is the transpose of the tangentToWorld transformation matrix
+    FP mat3 tangentToWorldMatrix = mat3(wFixedTangent, wBinormal, wNormal);
+    FP mat3 worldToTangentMatrix = transpose(tangentToWorldMatrix);
+    return worldToTangentMatrix;
+}