From 5299badf58fdc199d353e8f8070812df3e8b24ad Mon Sep 17 00:00:00 2001
From: Luke Benstead <kazade@gmail.com>
Date: Wed, 3 Apr 2024 22:09:35 +0100
Subject: [PATCH] Only submit trailing vertices if the previous triangle was
 visible

---
 GL/platforms/sh4.c                 | 24 ++++++++++++------------
 samples/zclip_trianglestrip/main.c |  2 +-
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/GL/platforms/sh4.c b/GL/platforms/sh4.c
index 8503136..53227e4 100644
--- a/GL/platforms/sh4.c
+++ b/GL/platforms/sh4.c
@@ -216,7 +216,7 @@ void SceneListSubmit(Vertex* vertices, int n) {
 #define SUBMIT_QUEUED_VERTEX(sflags) \
     do { if(queued_vertex) { queued_vertex->flags = (sflags); _glPushHeaderOrVertex(queued_vertex); queued_vertex = NULL; } } while(0)
 
-    uint8_t visible_mask = 0;
+    int visible_mask = 0;
 
     sq = SQ_BASE_ADDRESS;
 
@@ -237,21 +237,21 @@ void SceneListSubmit(Vertex* vertices, int n) {
             // we need to finalize this strip and move on
             SUBMIT_QUEUED_VERTEX(qv.flags);
 
-            _glPerspectiveDivideVertex(v0, h);
-            _glPushHeaderOrVertex(v0);
+            // If the last triangle was all visible, we need
+            // to submit the last two vertices, any clipped triangles
+            // would've 
+            if(visible_mask == ALL_VISIBLE) {
+                _glPerspectiveDivideVertex(v0, h);
+                _glPushHeaderOrVertex(v0);
 
-            _glPerspectiveDivideVertex(v1, h);
-            _glPushHeaderOrVertex(v1);
-            i += 2;
+                _glPerspectiveDivideVertex(v1, h);
+                _glPushHeaderOrVertex(v1);
+                i += 2;
+            }
             continue;
         }
 
-        assert(!is_header(v2));
-
-        // FIXME: What if v1 or v2 are headers? Should we handle that or just
-        // assume the user has done something weird and all bets are off?
-
-        int visible_mask = (
+        visible_mask = (
             (v0->xyz[2] >= -v0->w) << 0 |
             (v1->xyz[2] >= -v1->w) << 1 |
             (v2->xyz[2] >= -v2->w) << 2
diff --git a/samples/zclip_trianglestrip/main.c b/samples/zclip_trianglestrip/main.c
index 4960c1c..064add8 100644
--- a/samples/zclip_trianglestrip/main.c
+++ b/samples/zclip_trianglestrip/main.c
@@ -64,7 +64,7 @@ int check_start() {
     return 0;
 }
 
-static GLfloat movement = 0.0f;
+static GLfloat movement = -10.0f;
 static GLfloat rotation = 0.0f;
 
 void update_movement() {