From d218896b63c20e1eb0938459100446b6b0473437 Mon Sep 17 00:00:00 2001
From: Zeno Rogue <zeno@attnam.com>
Date: Fri, 14 Oct 2022 00:54:31 +0200
Subject: [PATCH] sl2:: more projections allowed

---
 hypgraph.cpp | 7 +++++++
 models.cpp   | 2 +-
 shaders.cpp  | 8 ++++++++
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/hypgraph.cpp b/hypgraph.cpp
index f0065113..fa5d8d4c 100644
--- a/hypgraph.cpp
+++ b/hypgraph.cpp
@@ -744,6 +744,13 @@ EX void apply_other_model(shiftpoint H_orig, hyperpoint& ret, eModel md) {
     
     case mdHorocyclic: {
 
+      if(sl2) {
+        ret = unshift(H_orig);
+        ret *= .5;
+        ret[LDIM] = 1;
+        ret = lp_apply(ret);
+        break;
+        }
       find_zlev(H);
 
       apply_nil_rotation(H);
diff --git a/models.cpp b/models.cpp
index 41c94e9e..e79ca405 100644
--- a/models.cpp
+++ b/models.cpp
@@ -192,7 +192,7 @@ EX namespace models {
       if(among(pm, mdBall, mdHemisphere)) return false;
       return PIU(model_available(pm));
       }
-    if(sl2) return pm == mdGeodesic;
+    if(sl2) return among(pm, mdGeodesic, mdEquidistant, mdHorocyclic, mdPerspective);
     if(nonisotropic) return among(pm, mdDisk, mdPerspective, mdHorocyclic, mdGeodesic, mdEquidistant, mdFisheye, mdLiePerspective, mdLieOrthogonal);
     if(sphere && (pm == mdHalfplane || pm == mdBall))
       return false;
diff --git a/shaders.cpp b/shaders.cpp
index 51d63c4b..0ff264ad 100644
--- a/shaders.cpp
+++ b/shaders.cpp
@@ -349,6 +349,14 @@ shared_ptr<glhr::GLprogram> write_shader(flagtype shader_flags) {
     }
   else if(pmodel == mdPerspective) {
     shader_flags |= SF_PERS3 | SF_DIRECT;
+    if(sl2) {
+      vsh += "uniform mediump float uIndexSL;\n";
+      coordinator +=
+        "float ca = cos(uIndexSL); float sa = -sin(uIndexSL);\n"
+        "vec4 h1 = t;\n"
+        "t[2] = h1[2] * ca - h1[3] * sa; t[3] = 1.;\n"
+        "t[0] = h1[0] * ca - h1[1] * sa; t[1] = h1[1] * ca + h1[0] * sa;\n";
+      }
     #if CAP_VR
     if(vrhr::rendering() && hyperbolic && vrhr::eyes != vrhr::eEyes::truesim) {
       azi_hyperbolic = true;