From 881175630170a91441bb7c70106598b2afd4438c Mon Sep 17 00:00:00 2001
From: Adam <Adam@sigterm.info>
Date: Tue, 8 Feb 2022 11:14:11 -0500
Subject: [PATCH] gpu: replace count_prio_offset switch with loop

Nvidia drivers seem to compile the switch with fallthrough as a 19 level
nested if, and inlines the code from the fallthrough cases into each.

The hd devs have identified this as a potential source of the
artifacting that happens on some cards due to the number of nested
branches.

Replace the switch with a simple loop, which also is about 7% of the
generated code size of the switch.
---
 .../client/plugins/gpu/priority_render.cl     | 45 +++----------------
 .../client/plugins/gpu/priority_render.glsl   | 45 +++----------------
 2 files changed, 14 insertions(+), 76 deletions(-)

diff --git a/runelite-client/src/main/resources/net/runelite/client/plugins/gpu/priority_render.cl b/runelite-client/src/main/resources/net/runelite/client/plugins/gpu/priority_render.cl
index 6f1a04470c..4f3ecd4132 100644
--- a/runelite-client/src/main/resources/net/runelite/client/plugins/gpu/priority_render.cl
+++ b/runelite-client/src/main/resources/net/runelite/client/plugins/gpu/priority_render.cl
@@ -62,52 +62,21 @@ int priority_map(int p, int distance, int _min10, int avg1, int avg2, int avg3)
         return 17;
       }
     default:
-      return -1;
+      // this can't happen unless an invalid priority is sent. just assume 0.
+      return 0;
   }
 }
 
 // calculate the number of faces with a lower adjusted priority than
 // the given adjusted priority
 int count_prio_offset(__local struct shared_data *shared, int priority) {
+  // this shouldn't ever be outside of (0, 17) because it is the return value from priority_map
+  priority = clamp(priority, 0, 17);
   int total = 0;
-  switch (priority) {
-    case 17:
-      total += shared->totalMappedNum[16];
-    case 16:
-      total += shared->totalMappedNum[15];
-    case 15:
-      total += shared->totalMappedNum[14];
-    case 14:
-      total += shared->totalMappedNum[13];
-    case 13:
-      total += shared->totalMappedNum[12];
-    case 12:
-      total += shared->totalMappedNum[11];
-    case 11:
-      total += shared->totalMappedNum[10];
-    case 10:
-      total += shared->totalMappedNum[9];
-    case 9:
-      total += shared->totalMappedNum[8];
-    case 8:
-      total += shared->totalMappedNum[7];
-    case 7:
-      total += shared->totalMappedNum[6];
-    case 6:
-      total += shared->totalMappedNum[5];
-    case 5:
-      total += shared->totalMappedNum[4];
-    case 4:
-      total += shared->totalMappedNum[3];
-    case 3:
-      total += shared->totalMappedNum[2];
-    case 2:
-      total += shared->totalMappedNum[1];
-    case 1:
-      total += shared->totalMappedNum[0];
-    case 0:
-      return total;
+  for (int i = 0; i < priority; i++) {
+    total += shared->totalMappedNum[i];
   }
+  return total;
 }
 
 void get_face(
diff --git a/runelite-client/src/main/resources/net/runelite/client/plugins/gpu/priority_render.glsl b/runelite-client/src/main/resources/net/runelite/client/plugins/gpu/priority_render.glsl
index 90af8d41f0..fc6f9ddfed 100644
--- a/runelite-client/src/main/resources/net/runelite/client/plugins/gpu/priority_render.glsl
+++ b/runelite-client/src/main/resources/net/runelite/client/plugins/gpu/priority_render.glsl
@@ -62,52 +62,21 @@ int priority_map(int p, int distance, int _min10, int avg1, int avg2, int avg3)
         return 17;
       }
     default:
-      return -1;
+      // this can't happen unless an invalid priority is sent. just assume 0.
+      return 0;
   }
 }
 
 // calculate the number of faces with a lower adjusted priority than
 // the given adjusted priority
 int count_prio_offset(int priority) {
+  // this shouldn't ever be outside of (0, 17) because it is the return value from priority_map
+  priority = clamp(priority, 0, 17);
   int total = 0;
-  switch (priority) {
-    case 17:
-      total += totalMappedNum[16];
-    case 16:
-      total += totalMappedNum[15];
-    case 15:
-      total += totalMappedNum[14];
-    case 14:
-      total += totalMappedNum[13];
-    case 13:
-      total += totalMappedNum[12];
-    case 12:
-      total += totalMappedNum[11];
-    case 11:
-      total += totalMappedNum[10];
-    case 10:
-      total += totalMappedNum[9];
-    case 9:
-      total += totalMappedNum[8];
-    case 8:
-      total += totalMappedNum[7];
-    case 7:
-      total += totalMappedNum[6];
-    case 6:
-      total += totalMappedNum[5];
-    case 5:
-      total += totalMappedNum[4];
-    case 4:
-      total += totalMappedNum[3];
-    case 3:
-      total += totalMappedNum[2];
-    case 2:
-      total += totalMappedNum[1];
-    case 1:
-      total += totalMappedNum[0];
-    case 0:
-      return total;
+  for (int i = 0; i < priority; i++) {
+      total += totalMappedNum[i];
   }
+  return total;
 }
 
 void get_face(uint localId, modelinfo minfo, int cameraYaw, int cameraPitch,