From e6db0986ce19057cb3a3b946ef2ad6884178f7a1 Mon Sep 17 00:00:00 2001
From: Luke Benstead <kazade@gmail.com>
Date: Wed, 4 Nov 2020 19:54:04 +0000
Subject: [PATCH] Fix clipping issues

---
 GL/flush.c                  | 34 ++++++++++++++++++++++++++--------
 GL/flush.h                  | 14 ++------------
 tests/test_nearz_clipping.h | 30 +++++++++++++++++++++++++++---
 3 files changed, 55 insertions(+), 23 deletions(-)

diff --git a/GL/flush.c b/GL/flush.c
index 38f1329..dc95b63 100644
--- a/GL/flush.c
+++ b/GL/flush.c
@@ -250,15 +250,19 @@ static ListIterator* clip110(ListIterator* it) {
     interpolate_vertex(it->triangle[0], it->triangle[2], gen3);
     interpolate_vertex(it->triangle[1], it->triangle[2], gen4);
 
-    assert(isVisible(gen1));
-    assert(isVisible(gen2));
-    assert(isVertex(gen1));
-    assert(isVertex(gen2));
-
     /* Return A */
     it->active = gen1;
     it->stack_idx--;
 
+    assert(isVisible(gen1));
+    assert(isVisible(gen2));
+    assert(isVisible(gen3));
+    assert(isVisible(gen4));
+    assert(isVertex(gen1));
+    assert(isVertex(gen2));
+    assert(isVertex(gen3));
+    assert(isVertex(gen4));
+
     return finish_clip(it);
 }
 
@@ -278,14 +282,14 @@ static ListIterator* clip101(ListIterator* it) {
 
     /* First and last need to be the same*/
     *gen1 = *it->triangle[0];
-    *gen3 = *it->triangle[2];
+    *gen2 = *it->triangle[2];
 
     gen1->flags = PVR_CMD_VERTEX;
     gen2->flags = PVR_CMD_VERTEX;
     gen3->flags = PVR_CMD_VERTEX;
     gen4->flags = PVR_CMD_VERTEX_EOL; /* 4 is now last in the list */
 
-    interpolate_vertex(it->triangle[0], it->triangle[1], gen2);
+    interpolate_vertex(it->triangle[0], it->triangle[1], gen3);
     interpolate_vertex(it->triangle[1], it->triangle[2], gen4);
 
     it->active = gen1;
@@ -343,7 +347,7 @@ static ListIterator* clip001(ListIterator* it) {
     gen3->flags = PVR_CMD_VERTEX_EOL;
 
     interpolate_vertex(it->triangle[0], it->triangle[2], gen1);
-    interpolate_vertex(it->triangle[1], it->triangle[2], gen2);
+    interpolate_vertex(it->triangle[2], it->triangle[1], gen2);
 
     it->active = gen1;
     it->stack_idx--;
@@ -378,6 +382,20 @@ static ListIterator* clip010(ListIterator* it) {
     return finish_clip(it);
 }
 
+ListIterator* _glIteratorBegin(void* src, int n) {
+    TRACE();
+
+    ListIterator* it = (ListIterator*) malloc(sizeof(ListIterator));
+    it->remaining = n - 1;
+    it->active = (Vertex*) src;
+    it->src = it->active + 1;
+    it->stack_idx = -1;
+    it->triangle_count = 0;
+    it->visibility = 0;
+    it->triangle[0] = it->triangle[1] = it->triangle[2] = NULL;
+    return (n) ? it : NULL;
+}
+
 ListIterator* _glIteratorNext(ListIterator* it) {
     TRACE();
 
diff --git a/GL/flush.h b/GL/flush.h
index 760e3e4..279ccc9 100644
--- a/GL/flush.h
+++ b/GL/flush.h
@@ -41,17 +41,7 @@ typedef struct {
     uint8_t padding;
 } ListIterator;
 
-inline ListIterator* _glIteratorBegin(void* src, int n) {
-    ListIterator* it = (ListIterator*) malloc(sizeof(ListIterator));
-    it->remaining = n - 1;
-    it->active = (Vertex*) src;
-    it->src = it->active + 1;
-    it->stack_idx = -1;
-    it->triangle_count = 0;
-    it->visibility = 0;
-    it->triangle[0] = it->triangle[1] = it->triangle[2] = NULL;
-    return (n) ? it : NULL;
-}
+ListIterator* _glIteratorBegin(void* src, int n);
 
 GL_FORCE_INLINE GLboolean isVertex(const Vertex* vertex) {
     assert(vertex);
@@ -66,7 +56,7 @@ GL_FORCE_INLINE GLboolean isVisible(const Vertex* vertex) {
     TRACE();
 
     assert(vertex != NULL);
-    return vertex->w >= -0.00001f; // && vertex->xyz[2] >= -vertex->w;
+    return vertex->w > 0.0000f; // && vertex->xyz[2] >= -vertex->w;
 }
 
 ListIterator* _glIteratorNext(ListIterator* it);
diff --git a/tests/test_nearz_clipping.h b/tests/test_nearz_clipping.h
index 4dd28ba..0469d4a 100644
--- a/tests/test_nearz_clipping.h
+++ b/tests/test_nearz_clipping.h
@@ -53,9 +53,9 @@ private:
 #define assert_vertex_equal(v, x, y, z) \
     assert_is_not_null(v); \
     printf("> %f, %f, %f\n", v->xyz[0], v->xyz[1], v->xyz[2]); \
-    assert_equal(v->xyz[0], x); \
-    assert_equal(v->xyz[1], y); \
-    assert_equal(v->xyz[2], z); \
+    assert_close(v->xyz[0], x, 0.0001f); \
+    assert_close(v->xyz[1], y, 0.0001f); \
+    assert_close(v->xyz[2], z, 0.0001f); \
 
 #define assert_is_header(v) \
     assert_false(isVertex(v)); \
@@ -202,6 +202,30 @@ public:
     }
 
     void test_clipping_101() {
+        VertexBuilder builder;
+
+        auto list = builder.
+            add_header().
+            add(1, 1, 2, 1).
+            add(1, 0, 2, -1).
+            add_last(0, 1, 2, 1).done();
+
+        ListIterator* it = _glIteratorBegin(list.first, list.second);
+        Vertex* v0 = it->active;
+        assert_is_not_null(v0);
+        assert_false(isVertex(v0)); // Should be a header
+
+        it = _glIteratorNext(it);
+        assert_is_not_null(it);
+        assert_vertex_equal(it->active, 1, 1, 2);
+
+        it = _glIteratorNext(it);
+        assert_is_not_null(it);
+        assert_vertex_equal(it->active, 0, 1, 2);
+
+        it = _glIteratorNext(it);
+        assert_is_not_null(it);
+        assert_vertex_equal(it->active, 1, 0.5f, 2);
 
     }