From bc2755ace841cdc5dee12bb55ac0bbc5dfc0b25e Mon Sep 17 00:00:00 2001
From: Donovan Hutchence <slimbuck7@gmail.com>
Date: Wed, 23 Oct 2024 14:02:06 +0100
Subject: [PATCH] Stop clipping splats to front and back camera planes (#229)

---
 src/shaders/splat-shader.ts | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/shaders/splat-shader.ts b/src/shaders/splat-shader.ts
index 3a9ca1c..67f2099 100644
--- a/src/shaders/splat-shader.ts
+++ b/src/shaders/splat-shader.ts
@@ -63,10 +63,9 @@ void main(void)
     // handle transforms
     mat4 model_view = matrix_view * model;
     vec4 splat_cam = model_view * vec4(center, 1.0);
-    vec4 splat_proj = matrix_projection * splat_cam;
 
     // cull behind camera
-    if (splat_proj.z < -splat_proj.w) {
+    if (splat_cam.z > 0.0) {
         gl_Position = discardVec;
         return;
     }
@@ -83,8 +82,12 @@ void main(void)
         return;
     }
 
+    vec4 splat_proj = matrix_projection * splat_cam;
     gl_Position = splat_proj + vec4((vertex_position.x * v1v2.xy + vertex_position.y * v1v2.zw) / viewport * splat_proj.w, 0, 0);
 
+    // ensure splats aren't clipped by front and back clipping planes
+    gl_Position.z = clamp(gl_Position.z, -abs(gl_Position.w), abs(gl_Position.w));
+
     texCoord = vertex_position.xy * 0.5;
 
     #ifdef FORWARD_PASS