From 38eb8c51221bb62347dc3691668d7d5b1c526aa4 Mon Sep 17 00:00:00 2001
From: Zeno Rogue <zeno@attnam.com>
Date: Mon, 28 Dec 2020 22:00:56 +0100
Subject: [PATCH] disk model in Euclidean and hyperbolic

---
 glhr.cpp     |  6 ++++++
 hypgraph.cpp | 21 ++++++++++++++++++++-
 shaders.cpp  | 38 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/glhr.cpp b/glhr.cpp
index 6721cf47..d3017088 100644
--- a/glhr.cpp
+++ b/glhr.cpp
@@ -298,6 +298,7 @@ struct GLprogram {
   GLint uFog, uFogColor, uColor, tTexture, tInvExpTable, tAirMap, uMV, uProjection, uAlpha, uFogBase, uPP;
   GLint uPRECX, uPRECY, uPRECZ, uIndexSL, uIterations, uLevelLines, uSV, uRadarTransform;
   GLint uRotSin, uRotCos, uRotNil;
+  GLint uDepthScaling, uCamera, uDepth;
   
   flagtype shader_flags;
   
@@ -364,6 +365,7 @@ GLprogram::GLprogram(string vsh, string fsh) {
     uAlpha = -1;
     uLevelLines = -1;
     uFogColor = -1;
+    uDepthScaling = uCamera = uDepth = -1;
     
     uColor = tTexture = tInvExpTable = tAirMap = -1;
     uFogBase = -1;
@@ -426,6 +428,10 @@ GLprogram::GLprogram(string vsh, string fsh) {
   tInvExpTable = glGetUniformLocation(_program, "tInvExpTable");
   tAirMap = glGetUniformLocation(_program, "tAirMap");
 
+  uDepth = glGetUniformLocation(_program, "uDepth");
+  uDepthScaling = glGetUniformLocation(_program, "uDepthScaling");
+  uCamera = glGetUniformLocation(_program, "uCamera");
+
   uPRECX = glGetUniformLocation(_program, "PRECX");
   uPRECY = glGetUniformLocation(_program, "PRECY");
   uPRECZ = glGetUniformLocation(_program, "PRECZ");
diff --git a/hypgraph.cpp b/hypgraph.cpp
index 16adc403..713ef0f6 100644
--- a/hypgraph.cpp
+++ b/hypgraph.cpp
@@ -411,7 +411,7 @@ EX void apply_other_model(shiftpoint H_orig, hyperpoint& ret, eModel md) {
     case mdBall: {
       ld zlev = find_zlev(H);
       
-      ld zl = vid.depth-geom3::factor_to_lev(zlev);
+      ld zl = vid.depth-geom3::factor_to_lev(zlev) * pconf.depth_scaling;
   
       ballmodel(ret, atan2(H), hdist0(H), zl);
       break;      
@@ -434,6 +434,25 @@ EX void apply_other_model(shiftpoint H_orig, hyperpoint& ret, eModel md) {
         ret[3] = 1; 
         break;
         }
+      if(vrhr::state == 2) {
+        ld zlev = find_zlev(H);
+        ld zl = vid.depth-geom3::factor_to_lev(zlev) * pconf.depth_scaling;
+
+        ld d = hdist0(H);
+        ld dd = hypot_d(2, H);
+
+        hyperpoint H1 = ypush(vid.camera) * xpush(d) * ypush0(zl);
+        ld tzh = pconf.alpha + H1[2];
+        ld ax = H1[0] / tzh;
+        ld ay = H1[1] / tzh;
+  
+        ret[0] = ax * H[0] / dd;
+        ret[1] = ax * H[1] / dd;
+        ret[2] = ay;
+        
+        models::apply_vr(ret[2], ret[1]);
+        return;
+        }
       ld tz = get_tz(H);
       if(!pconf.camera_angle) {
         ret[0] = H[0] / tz;
diff --git a/shaders.cpp b/shaders.cpp
index 804192c6..4f40f528 100644
--- a/shaders.cpp
+++ b/shaders.cpp
@@ -155,6 +155,35 @@ shared_ptr<glhr::GLprogram> write_shader(flagtype shader_flags) {
     }
   else if(!vid.consider_shader_projection) {
     shader_flags |= SF_PIXELS;
+    }        
+  else if(among(pmodel, mdDisk, mdBall) && GDIM == 2 && vrhr::state == 2 && !sphere) {
+    shader_flags |= SF_DIRECT | SF_BOX;
+    vsh += "uniform mediump float uAlpha, uDepth, uDepthScaling, uCamera;";
+    
+    if(hyperbolic) coordinator += 
+      "float zlev = sqrt(t.z*t.z-t.x*t.x-t.y*t.y);\n"
+      "float zl = uDepth - uDepthScaling * (uDepth - atanh(tanh(uDepth)/zlev));\n"
+      "float dd = sqrt(t.x*t.x+t.y*t.y);\n"
+      "float d  = acosh(t.z/zlev);\n"
+      "float uz = uAlpha + cosh(zl) * cosh(d) * cosh(uCamera) + sinh(zl) * sinh(uCamera);\n"
+      "float ux = cosh(zl) * sinh(d) / uz;\n"      
+      "t.xy = ux * t.xy / dd;\n"
+      "t.z = (sinh(zl) * cosh(uCamera) + sinh(uCamera) * cosh(zl) * cosh(d)) / uz;\n"
+      ;
+    
+    else if(euclid) coordinator +=
+      "t.z = uDepth * (1. - (t.z - 1.) * uDepthScaling) + uAlpha + uCamera;\n";
+
+    else if(sphere) coordinator += 
+      "float zlev = sqrt(t.z*t.z+t.x*t.x+t.y*t.y);\n"
+      "float zl = uDepth - uDepthScaling * (uDepth - atan(tan(uDepth)/zlev));\n"
+      "float dd = sqrt(t.x*t.x+t.y*t.y);\n"
+      "float d  = acos(t.z/zlev);\n"
+      "float uz = uAlpha + cos(zl) * cos(d) * cos(uCamera) + sin(zl) * sin(uCamera);\n"
+      "float ux = cos(zl) * sin(d) / uz;\n"
+      "t.xy = ux * t.xy / dd;\n"
+      "t.z = (sin(uCamera) * cos(zl) * cos(d) - sin(zl) * cos(uCamera)) / uz;\n"
+      ;
     }
   else if(pmodel == mdDisk && MDIM == 3 && !spherespecial && !prod) {
     shader_flags |= SF_DIRECT;
@@ -615,6 +644,15 @@ void display_data::set_projection(int ed, ld shift) {
   if(selected->uAlpha != -1)
     glhr::set_ualpha(pconf.alpha);
 
+  if(selected->uDepth != -1)
+    glUniform1f(selected->uDepth, vid.depth);
+
+  if(selected->uCamera != -1)
+    glUniform1f(selected->uCamera, vid.camera);
+
+  if(selected->uDepthScaling != -1)
+    glUniform1f(selected->uDepthScaling, pconf.depth_scaling);
+
   if(selected->uLevelLines != -1) {
     glUniform1f(selected->uLevelLines, levellines);
     }