From 59ff4c226699e4e9072e9f8c03574c4732b0547e Mon Sep 17 00:00:00 2001
From: Zeno Rogue <zeno@attnam.com>
Date: Mon, 3 Sep 2018 16:32:11 +0200
Subject: [PATCH] depth inversion in rug (used in pentagonal exploration)

---
 hyper.h | 1 +
 rug.cpp | 8 +++++---
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/hyper.h b/hyper.h
index 1771f05e..94df37ee 100644
--- a/hyper.h
+++ b/hyper.h
@@ -1225,6 +1225,7 @@ extern eGeometry gwhere;
 extern bool no_fog;
 extern ld lowrug, hirug, ruggospeed;
 extern GLuint alternate_texture;
+extern bool invert_depth;
 #endif
   }
 
diff --git a/rug.cpp b/rug.cpp
index 9dec74f6..e37d720a 100644
--- a/rug.cpp
+++ b/rug.cpp
@@ -1264,6 +1264,8 @@ ld lowrug = 1e-2, hirug = 1e3;
 
 GLuint alternate_texture;
 
+bool invert_depth;
+
 void drawRugScene() {
   glbuf->use_as_texture();
   if(alternate_texture)
@@ -1274,16 +1276,16 @@ void drawRugScene() {
   else
     glhr::colorClear(backcolor << 8 | 0xFF);
 #ifdef GLES_ONLY
-  glClearDepthf(1.0f);
+  glClearDepthf(invert_depth ? -1.0f : 1.0f);
 #else
-  glClearDepth(1.0f);
+  glClearDepth(invert_depth ? -1.0f : 1.0f);
 #endif
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
   
   glDisable(GL_BLEND);
   glhr::switch_mode(glhr::gmLightFog);
   glhr::set_depthtest(true);
-  glDepthFunc(GL_LESS);
+  glDepthFunc(invert_depth ? GL_GREATER : GL_LESS);
   
   for(int ed=stereo::active() && stereo::mode != stereo::sODS ? -1 : 0; ed < 2; ed += 2) {
     use_precompute = false;