From 140183b55a90356fd81e3e33c0cbf18b56dd29fd Mon Sep 17 00:00:00 2001
From: Matthew Scroggs <matthew.w.scroggs@gmail.com>
Date: Sat, 8 Jun 2024 13:40:48 +0100
Subject: [PATCH] correct isometric level (#51)

---
 CHANGELOG_SINCE_LAST_VERSION.md |  1 +
 mathsteroids.js                 | 23 ++++++++++++++---------
 titlescreen.js                  | 12 +++++++-----
 3 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/CHANGELOG_SINCE_LAST_VERSION.md b/CHANGELOG_SINCE_LAST_VERSION.md
index 1711bf3..0148496 100644
--- a/CHANGELOG_SINCE_LAST_VERSION.md
+++ b/CHANGELOG_SINCE_LAST_VERSION.md
@@ -1 +1,2 @@
 - Fix control buttons bug
+- Correct isometric level
diff --git a/mathsteroids.js b/mathsteroids.js
index 24b9b63..3d5105f 100644
--- a/mathsteroids.js
+++ b/mathsteroids.js
@@ -791,12 +791,16 @@ function draw_shape(){
                 var vangle = 0
                 var hangle = 0
                 var N = 100
-                if(circle==1){hangle=3*Math.PI/4}
+                if(circle==1){
+                    hangle=3*Math.PI/4
+                }
                 var prev = vangle
                 var preh = hangle
-                for(var i=0;i<N;i++){
-                    if(circle==0){hangle += Math.PI*2/N}
-                    else{vangle += Math.PI*2/N}
+                for(var i=1;i<=N;i++){
+                    hangle += Math.PI*2/N
+                    if(circle==1){
+                        vangle = Math.atan(Math.cos(hangle)+Math.sin(hangle))
+                    }
                     add_line_to_draw(Array(preh,prev,hangle,vangle))
                     prev = vangle
                     preh = hangle
@@ -1805,7 +1809,8 @@ function add_line_to_draw(thing){
         var vangle = (thing[1]+thing[3])/2
         var x = Math.cos(vangle) * Math.cos(hangle)
         var y = Math.cos(vangle) * Math.sin(hangle)
-        if(x+y<-0.1){
+        var z = Math.sin(vangle)
+        if(x+y-z<-0.1){
             back_points[back_points.length] = thing
             return
         }
@@ -2165,11 +2170,11 @@ function isometric_xy(hangle,vangle){
     var x = RADIUS * Math.cos(vangle) * Math.cos(hangle)
     var y = RADIUS * Math.cos(vangle) * Math.sin(hangle)
     var z = RADIUS * Math.sin(vangle)
-    var x2 = (x-y) * Math.sin(30)
-    var y2 = z + (x+y) * Math.cos(30)
+    var x2 = (y-x) * Math.cos(Math.PI/6)
+    var y2 = z + (x+y) * Math.sin(Math.PI/6)
     var out = {}
-    out["x"] = WIDTH/2 + x2/(2.2*RADIUS) * Math.min(HEIGHT, WIDTH)
-    out["y"] = HEIGHT/2 + y2/(2.2*RADIUS) * Math.min(HEIGHT, WIDTH)
+    out["x"] = WIDTH/2 + x2/(2.5*RADIUS) * Math.min(HEIGHT, WIDTH)
+    out["y"] = HEIGHT/2 + y2/(2.5*RADIUS) * Math.min(HEIGHT, WIDTH)
     return out
 }
 
diff --git a/titlescreen.js b/titlescreen.js
index 52d3858..ab127df 100644
--- a/titlescreen.js
+++ b/titlescreen.js
@@ -29,17 +29,19 @@ function draw_a_sphere(ctx, xcenter){
             var x = Math.cos(vangle) * Math.cos(hangle)
             var y = Math.cos(vangle) * Math.sin(hangle)
             var z = Math.sin(vangle)
-            var x2 = (x-y) * Math.sin(30)
-            var y2 = z + (x+y) * Math.cos(30)
+            var x2 = (x-y) * Math.cos(Math.PI/6)
+            var y2 = z + (x+y) * Math.sin(Math.PI/6)
             var x3 = xcenter + x2 * 100
             var y3 = HEIGHT/2 + y2 * 100
-            if(i==0 || (i%2==0 && x+y<-0.2)){
+            if(i==0 || (i%2==0 && x+y-z<-0.2)){
                 ctx.moveTo(x3,y3)
             } else {
                 ctx.lineTo(x3,y3)
             }
-            if(circle==0){hangle += Math.PI*2/N}
-            else{vangle += Math.PI*2/N}
+            hangle += Math.PI*2/N
+            if(circle==1){
+                vangle = Math.atan(Math.cos(hangle)+Math.sin(hangle))
+            }
         }
     }
 }