From f166d006c26446c413d44522f783522541842976 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Wed, 18 Sep 2013 21:44:51 +0200
Subject: [PATCH] Shaders: `const` for readonly variables is since GLSL 4.20.

---
 src/Shaders/MeshVisualizer.frag | 3 +++
 src/Shaders/MeshVisualizer.geom | 4 ++++
 src/Shaders/Phong.frag          | 4 ++++
 src/Shaders/compatibility.glsl  | 6 ++++++
 4 files changed, 17 insertions(+)

diff --git a/src/Shaders/MeshVisualizer.frag b/src/Shaders/MeshVisualizer.frag
index 5ec882ed0..981b30a8b 100644
--- a/src/Shaders/MeshVisualizer.frag
+++ b/src/Shaders/MeshVisualizer.frag
@@ -25,6 +25,9 @@
 #ifndef NEW_GLSL
 #define in varying
 #define fragmentColor gl_FragColor
+#endif
+
+#ifndef RUNTIME_CONST
 #define const
 #endif
 
diff --git a/src/Shaders/MeshVisualizer.geom b/src/Shaders/MeshVisualizer.geom
index 3043f38cf..f6a5f6e73 100644
--- a/src/Shaders/MeshVisualizer.geom
+++ b/src/Shaders/MeshVisualizer.geom
@@ -22,6 +22,10 @@
     DEALINGS IN THE SOFTWARE.
 */
 
+#ifndef RUNTIME_CONST
+#define const
+#endif
+
 layout(location = 1) uniform vec2 viewportSize;
 
 layout(triangles) in;
diff --git a/src/Shaders/Phong.frag b/src/Shaders/Phong.frag
index 3d98851f6..3390442f7 100644
--- a/src/Shaders/Phong.frag
+++ b/src/Shaders/Phong.frag
@@ -27,6 +27,10 @@
 #define color gl_FragColor
 #endif
 
+#ifndef RUNTIME_CONST
+#define const
+#endif
+
 #ifndef GL_ES
 #ifdef EXPLICIT_UNIFORM_LOCATION
 layout(location = 7) uniform vec3 lightColor = vec3(1.0, 1.0, 1.0);
diff --git a/src/Shaders/compatibility.glsl b/src/Shaders/compatibility.glsl
index 3534b4187..50e527d10 100644
--- a/src/Shaders/compatibility.glsl
+++ b/src/Shaders/compatibility.glsl
@@ -56,3 +56,9 @@
 #define mediump
 #define lowp
 #endif
+
+/* const qualifier can be used for readonly variables since GLSL 4.20, however
+   it's not supported even in ES 3.0 */
+#if !defined(GL_ES) && __VERSION__ >= 420
+#define RUNTIME_CONST
+#endif