From 2e4beb361c3a23692722454cc2dfb28ffe980ff1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Thu, 19 Jul 2018 15:35:17 +0200
Subject: [PATCH] TextureTools: don't require more than 8 texture units in
 distanceField().

ES2 contexts on iOS don't have more than that. It's weird, because ES3
contexts have 16.
---
 doc/changelog.dox                                | 6 ++++++
 src/Magnum/TextureTools/DistanceField.cpp        | 4 +++-
 src/Magnum/TextureTools/DistanceFieldShader.frag | 2 +-
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/doc/changelog.dox b/doc/changelog.dox
index 65f197657..57255ac32 100644
--- a/doc/changelog.dox
+++ b/doc/changelog.dox
@@ -122,6 +122,12 @@ See also:
     @ref Shaders::VertexColor::Color4 attribute specifiers for more convenient
     distinction between three- and four-component vertex color attribute.
 
+@subsubsection changelog-latest-changes-texturetools TextureTools library
+
+-   Fixed @ref TextureTools::distanceField() to not require more than 8 texture
+    units, which is the limit on all iOS ES2 contexts, independently on the
+    device (ES3 contexts have 16).
+
 @subsubsection changelog-latest-changes-trade Trade library
 
 -   @ref Trade::PhongMaterialData now contains well-defined color values
diff --git a/src/Magnum/TextureTools/DistanceField.cpp b/src/Magnum/TextureTools/DistanceField.cpp
index 01a53dee7..1289dcaf9 100644
--- a/src/Magnum/TextureTools/DistanceField.cpp
+++ b/src/Magnum/TextureTools/DistanceField.cpp
@@ -75,7 +75,9 @@ class DistanceFieldShader: public GL::AbstractShaderProgram {
         }
 
     private:
-        enum: Int { TextureUnit = 8 };
+        /* ES2 on iOS (apparently independent on the device) has only 8 texture
+           units, so be careful to not step over that. ES3 has 16. */
+        enum: Int { TextureUnit = 7 };
 
         Int radiusUniform{0},
             scalingUniform{1},
diff --git a/src/Magnum/TextureTools/DistanceFieldShader.frag b/src/Magnum/TextureTools/DistanceFieldShader.frag
index f48500048..c2b3e87e7 100644
--- a/src/Magnum/TextureTools/DistanceFieldShader.frag
+++ b/src/Magnum/TextureTools/DistanceFieldShader.frag
@@ -46,7 +46,7 @@ uniform mediump vec2 scaling;
 #endif
 
 #ifdef EXPLICIT_TEXTURE_LAYER
-layout(binding = 8) uniform sampler2D textureData;
+layout(binding = 7) uniform sampler2D textureData;
 #else
 uniform lowp sampler2D textureData;
 #endif