From 7c4874bdad593b1ee39d62ce61c82891f92f9ef2 Mon Sep 17 00:00:00 2001
From: Grant Sanderson <grant@3blue1brown.com>
Date: Tue, 9 Jun 2020 17:12:52 -0700
Subject: [PATCH] Changed how focal_distance works

---
 manimlib/camera/camera.py             |  2 +-
 manimlib/shaders/get_gl_Position.glsl | 18 ++++++++++--------
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/manimlib/camera/camera.py b/manimlib/camera/camera.py
index cf7040b9..3d18716a 100644
--- a/manimlib/camera/camera.py
+++ b/manimlib/camera/camera.py
@@ -30,7 +30,7 @@ class CameraFrame(Mobject):
         "center_point": ORIGIN,
         # Theta, phi, gamma
         "euler_angles": [0, 0, 0],
-        "focal_distance": 5,
+        "focal_distance": 3,
     }
 
     def init_points(self):
diff --git a/manimlib/shaders/get_gl_Position.glsl b/manimlib/shaders/get_gl_Position.glsl
index a84c3951..bc7b405f 100644
--- a/manimlib/shaders/get_gl_Position.glsl
+++ b/manimlib/shaders/get_gl_Position.glsl
@@ -3,22 +3,24 @@
 // uniform float focal_distance;
 // uniform float is_fixed_in_frame;
 
-const vec2 DEFAULT_FRAME_SHAPE = vec2(8 * 16 / 9, 8);
+const vec2 DEFAULT_FRAME_SHAPE = vec2(8.0 * 16.0 / 9.0, 8.0);
 
 vec4 get_gl_Position(vec3 point){
-    vec4 result = vec4(point, 1);
+    vec4 result = vec4(point, 1.0);
     if(!bool(is_fixed_in_frame)){
-        result.x *= 2 / frame_shape.x;
-        result.y *= 2 / frame_shape.y;
+        result.x *= 2.0 / frame_shape.x;
+        result.y *= 2.0 / frame_shape.y;
+        result.z *= 2.0 / frame_shape.y;  // Should we give the frame a z shape?  Does that make sense?
         result.z /= focal_distance;
-        result.xy /= max(1 - point.z, 0);
-        // Todo, does this discontinuity add weirdness?  Theoretically, by this point,
+        result.xy /= max(1.0 - result.z, 0.0);
+        // Todo, does this discontinuity add weirdness?  Theoretically, by this result,
         // the z-coordiante of gl_Position only matter for z-indexing.  The reason
         // for thie line is to avoid agressive clipping of distant points.
         if(result.z < 0) result.z *= 0.1;
     } else{
-        result.x *= 2 / DEFAULT_FRAME_SHAPE.x;
-        result.y *= 2 / DEFAULT_FRAME_SHAPE.y;
+        result.x *= 2.0 / DEFAULT_FRAME_SHAPE.x;
+        result.y *= 2.0 / DEFAULT_FRAME_SHAPE.y;
     }
+    result.z *= -1;
     return result;
 }
\ No newline at end of file