1 files changed, 55 insertions, 0 deletions
diff --git a/res/effectlib/evalEnvironmentMap.glsllib b/res/effectlib/evalEnvironmentMap.glsllib
new file mode 100644
index 0000000..18431c7
--- /dev/null
+++ b/res/effectlib/evalEnvironmentMap.glsllib
@@ -0,0 +1,55 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 NVIDIA Corporation.
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt 3D Studio.
+**
+** $QT_BEGIN_LICENSE:GPL$
+** 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.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 or (at your option) any later version
+** approved by the KDE Free Qt Foundation. The licenses are as published by
+** the Free Software Foundation and appearing in the file LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+vec3 evalEnvironmentMap( in vec3 R, float roughness )
+{
+     // convert R to spherical texture coordinates
+     vec2 tc = vec2( ( atan( R.x, -R.z ) + PI ) / ( PI_TWO ), acos( -R.y ) / PI );
+
+    vec2 envMapSize = vec2( textureSize( uEnvironmentTexture, 0 ) );
+    float envMapLevels = log2( max( envMapSize.x, envMapSize.y ) );
+
+    // simulate textureQueryLod
+    vec2 dx = dFdx( tc * envMapSize.x );
+    vec2 dy = dFdy( tc * envMapSize.y );
+
+    float px = dot( dx, dx );
+    float py = dot( dy, dy );
+
+    float maxlod = 0.5 * log2( max( px, py ) ); // log2(sqrt()) = 0.5*log2()
+    float minlod = 0.5 * log2( min( px, py ) );
+
+    //float lod = max(0.0, maxlod - min( maxlod - minlod, envMapLevels ));
+    float lod = max(0.0, min( minlod, envMapLevels ));
+
+    float roughLevel = mix( lod , envMapLevels, roughness );
+
+    return( textureLod( uEnvironmentTexture, tc, roughLevel ).rgb );
+}