From 97058f24b460863b0cf042725893073f778feb47 Mon Sep 17 00:00:00 2001
From: mcrcortex <18544518+MCRcortex@users.noreply.github.com>
Date: Mon, 14 Jul 2025 19:43:34 +1000
Subject: [PATCH] fix backface culling

---
 .../assets/voxy/shaders/lod/mesh/frag.glsl    | 10 ++++
 .../assets/voxy/shaders/lod/mesh/mesh.glsl    | 46 +++++--------------
 .../assets/voxy/shaders/lod/mesh/task.glsl    |  4 +-
 3 files changed, 23 insertions(+), 37 deletions(-)

diff --git a/src/main/resources/assets/voxy/shaders/lod/mesh/frag.glsl b/src/main/resources/assets/voxy/shaders/lod/mesh/frag.glsl
index c70171ed..fd2ef5e8 100644
--- a/src/main/resources/assets/voxy/shaders/lod/mesh/frag.glsl
+++ b/src/main/resources/assets/voxy/shaders/lod/mesh/frag.glsl
@@ -85,4 +85,14 @@ void main() {
     colour = computeColour(colour);
 
     outColour = colour;
+
+
+    /*
+    uint hash = gl_PrimitiveID*1231421+123141;
+    hash ^= hash>>16;
+    hash = hash*1231421+123141;
+    hash ^= hash>>16;
+    hash = hash * 1827364925 + 123325621;
+    outColour = vec4(float(hash&15u)/15, float((hash>>4)&15u)/15, float((hash>>8)&15u)/15, 0);
+    */
 }
\ No newline at end of file
diff --git a/src/main/resources/assets/voxy/shaders/lod/mesh/mesh.glsl b/src/main/resources/assets/voxy/shaders/lod/mesh/mesh.glsl
index 8540bc66..14fcb4b4 100644
--- a/src/main/resources/assets/voxy/shaders/lod/mesh/mesh.glsl
+++ b/src/main/resources/assets/voxy/shaders/lod/mesh/mesh.glsl
@@ -47,6 +47,7 @@ uint getQuadId() {
 
     return (point&0xFFFFu)+(mid-(point>>16));
     */
+
     #pragma unroll
     for (uint i = 0; i<7; i++) {
         uint point = task.bins[i];
@@ -132,7 +133,7 @@ uint packVec4(vec4 vec) {
 }
 
 //===============
-vec3 cornerPos;
+vec3 cornerPos;//Does not include cameraSubPos to get exact need to - cameraSubPos
 vec2 axisFaceSize;
 uint face;
 
@@ -240,29 +241,6 @@ vec4 emitVertexPos(int corner) {
     return MVP*vec4(pointPos, 1.0);
 }
 
-bvec2 whatRender(vec4 p1, vec4 p2, vec4 p0, vec4 p3) {
-    vec2 ssmin = ((p1.xy/p1.w)+1)*screenSize;
-    vec2 ssmax = ssmin;
-
-    vec2 point = ((p2.xy/p2.w)+1)*screenSize;
-    ssmin = min(ssmin, point);
-    ssmax = max(ssmax, point);
-
-    point = ((p0.xy/p0.w)+1)*screenSize;
-    vec2 t0min = min(ssmin, point);
-    vec2 t0max = max(ssmax, point);
-
-    point = ((p3.xy/p3.w)+1)*screenSize;
-    vec2 t1min = min(ssmin, point);
-    vec2 t1max = max(ssmax, point);
-
-    //Possibly cull the triangles if they dont cover the center of a pixel on the screen (degen)
-    float degenBias = 0.01f;
-    bool t0draw = all(notEqual(round(t0min-degenBias),round(t0max+degenBias)));
-    bool t1draw = all(notEqual(round(t1min-degenBias),round(t1max+degenBias)));
-    return bvec2(t0draw, t1draw);
-}
-
 #ifdef HAS_STATISTICS
 layout(binding = STATISTICS_BUFFER_BINDING, std430) restrict buffer statisticsBuffer {
     uint visibleSectionCounts[5];
@@ -284,24 +262,20 @@ void main() {
     subgroupBarrier();
 
 
-    bool render = dot(faceNormal(face), cornerPos) <= 0;
+    bool render = dot(faceNormal(face), cornerPos-cameraSubPos) <= 0;
 
     if (render) {
         vec4 p1 = emitVertexPos(1);
         vec4 p2 = emitVertexPos(2);
         vec4 p0 = emitVertexPos(0);
         vec4 p3 = emitVertexPos(3);
-        bvec2 what = bvec2(true);//whatRender(p1, p2, p0, p3);
-        uint c = uint(what.x)+uint(what.y);
-        if (c == 0) {
-            return;//Early exit
-        }
+
         uvec4 data = createQuadData(quad);
 
         subgroupBarrier();
-        uint triId_ = subgroupExclusiveAdd(c);
+        uint triId_ = subgroupExclusiveAdd(2);
         uint triId = triId_;
-        uint vertId_ = subgroupExclusiveAdd(c==1?3:4);
+        uint vertId_ = subgroupExclusiveAdd(4);
         uint vertId = vertId_;
         uint idxId = triId*3;
 
@@ -310,7 +284,8 @@ void main() {
         //Emit common
         gl_MeshVerticesNV[vertId++].gl_Position = p1;
         gl_MeshVerticesNV[vertId++].gl_Position = p2;
-        if (what.x) {
+
+        {
             gl_PrimitiveIndicesNV[idxId++] = vertId_+0;
             gl_PrimitiveIndicesNV[idxId++] = vertId_+1;
             gl_PrimitiveIndicesNV[idxId++] = vertId;
@@ -320,7 +295,8 @@ void main() {
             primOut[triId].data = data;
             gl_MeshPrimitivesNV[triId++].gl_PrimitiveID = int(qid);
         }
-        if (what.y) {
+
+        {
             gl_PrimitiveIndicesNV[idxId++] = vertId_+0;
             gl_PrimitiveIndicesNV[idxId++] = vertId;
             gl_PrimitiveIndicesNV[idxId++] = vertId_+1;
@@ -333,7 +309,7 @@ void main() {
 
 
         subgroupBarrier();
-        uint count = subgroupMax(triId_+c);
+        uint count = subgroupMax(triId_+2);
         if (subgroupElect()) {
             gl_PrimitiveCountNV = count;
             #ifdef HAS_STATISTICS
diff --git a/src/main/resources/assets/voxy/shaders/lod/mesh/task.glsl b/src/main/resources/assets/voxy/shaders/lod/mesh/task.glsl
index 60e3e958..75af9960 100644
--- a/src/main/resources/assets/voxy/shaders/lod/mesh/task.glsl
+++ b/src/main/resources/assets/voxy/shaders/lod/mesh/task.glsl
@@ -35,11 +35,11 @@ layout(binding = STATISTICS_BUFFER_BINDING, std430) restrict buffer statisticsBu
 };
 #endif
 
-layout(std430) taskNV out Task {
+taskNV out Task {
     //Tightly packed, prefix sum + offset
     //uvec4 binA;
     //uvec4 binB;
-    layout(offset = 0) uint bins[8];
+    uint bins[8];
 
     vec3 cameraOffset;
     uint lodLvl;