From 65925cccdfaab9ed2b099b2aa150e1c536cd408e Mon Sep 17 00:00:00 2001
From: James Turner <zakalawe@mac.com>
Date: Tue, 5 May 2020 20:40:29 +0100
Subject: [PATCH] Enable old-style texture compression

Thanks to Dany for tracking this down!
---
 simgear/scene/model/ModelRegistry.cxx  |  8 -----
 simgear/scene/util/SGSceneFeatures.cxx | 46 +++++++++++++-------------
 2 files changed, 23 insertions(+), 31 deletions(-)

diff --git a/simgear/scene/model/ModelRegistry.cxx b/simgear/scene/model/ModelRegistry.cxx
index 9678a3ef..b2789bcd 100644
--- a/simgear/scene/model/ModelRegistry.cxx
+++ b/simgear/scene/model/ModelRegistry.cxx
@@ -113,9 +113,6 @@ protected:
     }
 };
 
-// disabling old-syle texture compression in favour of the 
-// texture-cache
-#if 0
 class SGTexCompressionVisitor : public SGTextureStateAttributeVisitor {
 public:
   virtual void apply(int, StateSet::RefAttributePair& refAttr)
@@ -146,7 +143,6 @@ public:
     }
   }
 };
-#endif
 
 class SGTexDataVarianceVisitor : public SGTextureStateAttributeVisitor {
 public:
@@ -644,12 +640,8 @@ osg::Node* OptimizeModelPolicy::optimize(osg::Node* node,
     SGTexDataVarianceVisitor dataVarianceVisitor;
     node->accept(dataVarianceVisitor);
 
-// disabling old-syle texture compression in favour of the 
-// texture-cache
-#if 0
     SGTexCompressionVisitor texComp;
     node->accept(texComp);
-#endif
     return node;
 }
 
diff --git a/simgear/scene/util/SGSceneFeatures.cxx b/simgear/scene/util/SGSceneFeatures.cxx
index f04ff858..04b46a01 100644
--- a/simgear/scene/util/SGSceneFeatures.cxx
+++ b/simgear/scene/util/SGSceneFeatures.cxx
@@ -69,29 +69,29 @@ SGSceneFeatures::instance()
 void
 SGSceneFeatures::applyTextureCompression(osg::Texture* texture) const
 {
-  // disable older texture-compression, since it interacts confusingly
-  // with the the runtime texture-cache. We always want to use 
-  // 'USE_IMAGE_DATA_FORMAT' when the texture-cache is active, since we
-  // decided whether to compress (or not) prior to this point.
-#if 0
-  switch (_textureCompression) {
-  case UseARBCompression:
-    texture->setInternalFormatMode(osg::Texture::USE_ARB_COMPRESSION);
-    break;
-  case UseDXT1Compression:
-    texture->setInternalFormatMode(osg::Texture::USE_S3TC_DXT1_COMPRESSION);
-    break;
-  case UseDXT3Compression:
-    texture->setInternalFormatMode(osg::Texture::USE_S3TC_DXT3_COMPRESSION);
-    break;
-  case UseDXT5Compression:
-    texture->setInternalFormatMode(osg::Texture::USE_S3TC_DXT5_COMPRESSION);
-    break;
-  default:
-    texture->setInternalFormatMode(osg::Texture::USE_IMAGE_DATA_FORMAT);
-    break;
-  }
-#endif
+    // if the texture cache is active, always use the file data format
+    if (_TextureCacheCompressionActive) {
+        texture->setInternalFormatMode(osg::Texture::USE_IMAGE_DATA_FORMAT);
+    } else {
+        // keep the older texture compression working, some people need it
+        switch (_textureCompression) {
+        case UseARBCompression:
+          texture->setInternalFormatMode(osg::Texture::USE_ARB_COMPRESSION);
+          break;
+        case UseDXT1Compression:
+          texture->setInternalFormatMode(osg::Texture::USE_S3TC_DXT1_COMPRESSION);
+          break;
+        case UseDXT3Compression:
+          texture->setInternalFormatMode(osg::Texture::USE_S3TC_DXT3_COMPRESSION);
+          break;
+        case UseDXT5Compression:
+          texture->setInternalFormatMode(osg::Texture::USE_S3TC_DXT5_COMPRESSION);
+          break;
+        default:
+          texture->setInternalFormatMode(osg::Texture::USE_IMAGE_DATA_FORMAT);
+          break;
+        }
+    }
 }
 
 bool