From 5442b2d4c9b4bfce4665799182149c5c93ccb003 Mon Sep 17 00:00:00 2001
From: Nico de Poel <ndepoel@gmail.com>
Date: Mon, 6 Feb 2023 12:50:25 +0100
Subject: [PATCH] Added a draw function for flat colored quads, useful for
 debugging

---
 draw.h  | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 world.c | 35 +++++++++++++++++++++--------------
 2 files changed, 70 insertions(+), 14 deletions(-)

diff --git a/draw.h b/draw.h
index 76e323a..82bac0d 100644
--- a/draw.h
+++ b/draw.h
@@ -80,6 +80,55 @@ static INLINE void draw_trianglestrip_lit(SVECTOR *verts, u_char numVerts, u_lon
     }
 }
 
+static INLINE void draw_quadstrip_flat(const ps1bsp_vertex_t *vertices, const ps1bsp_facevertex_t *faceVerts, u_char numVerts, P_COLOR *color, u_long *ot)
+{
+    const ps1bsp_facevertex_t *v0, *v1, *v2, *v3;
+    u_char i0, i1, i2, i3;
+    u_char head = 0;
+    u_char tail = numVerts;
+
+    // Initialize the first two vertices
+    i2 = --tail;
+    i3 = head++;
+
+    // Normally a quad strip would have (N-2)/2 quads, but we might end up with a sole triangle at the end which will be drawn as a collapsed quad
+    u_char numQuads = (numVerts - 1) >> 1;
+    for (u_char quadIdx = 0; quadIdx < numQuads; ++quadIdx)
+    {
+        i0 = i2;
+        i1 = i3;
+        i2 = --tail;
+        i3 = head++;
+
+        v0 = &faceVerts[i0];
+        v1 = &faceVerts[i1];
+        v2 = &faceVerts[i2];
+        v3 = &faceVerts[i3];
+
+        // Transform the first three vertices
+        gte_ldv3(&vertices[v0->index], &vertices[v1->index], &vertices[v2->index]);
+        gte_rtpt();     // Rotation, translation, perspective projection
+
+        // Draw a flat-shaded untextured colored quad
+        POLY_G4 *poly = (POLY_G4*)mem_prim(sizeof(POLY_G4));
+        gte_stsxy3_g3(poly);
+
+        // Transform the fourth vertex to complete the quad
+        gte_ldv0(&vertices[v3->index]);
+        gte_rtps();
+        gte_stsxy(&poly->x3);
+
+        setColorFast(&poly->r0, color);
+        setColorFast(&poly->r1, color);
+        setColorFast(&poly->r2, color);
+        setColorFast(&poly->r3, color);
+
+        setPolyG4(poly);
+        addPrim(ot, poly);
+        ++polyCount;
+    }
+}
+
 static INLINE void draw_quadstrip_lit(const ps1bsp_vertex_t *vertices, const ps1bsp_polyvertex_t *polyVerts, u_char numVerts, u_long *ot)
 {
     const ps1bsp_polyvertex_t *v0, *v1, *v2, *v3;
diff --git a/world.c b/world.c
index 29b6e3b..4cfcd43 100644
--- a/world.c
+++ b/world.c
@@ -5,22 +5,22 @@
 #include "draw.h"
 #include "frustum.h"
 
-static CVECTOR colors[] = 
+static P_COLOR colors[] = 
 {
-    { 255, 0, 0 },
-    { 0, 255, 0 },
-    { 0, 0, 255 },
-    { 255, 255, 0 },
-    { 255, 0, 255 },
-    { 0, 255, 255 },
-    { 128, 255, 0 },
-    { 255, 128, 0 },
-    { 128, 0, 255 },
-    { 255, 0, 128 },
-    { 0, 128, 255 },
-    { 0, 255, 128 },
+    { (255 << 16), 0 },
+    { (255 << 8), 0 },
+    { (255 << 0), 0 },
+    { (255 << 16) | (255 << 8), 0 },
+    { (255 << 16) | (255 << 0), 0 },
+    { (255 << 8)  | (255 << 0), 0 },
+    { (128 << 8)  | (255 << 8), 0 },
+    { (255 << 16) | (128 << 8), 0 },
+    { (128 << 16) | (255 << 0), 0 },
+    { (255 << 16) | (128 << 0), 0 },
+    { (128 << 8)  | (255 << 0), 0 },
+    { (128 << 8)  | (128 << 0), 0 },
 };
-static const int numColors = sizeof(colors) / sizeof(CVECTOR);
+static const int numColors = sizeof(colors) / sizeof(P_COLOR);
 
 // Set data pointers directly from an in-memory byte buffer
 #define LOAD_CHUNK(type, dst, num, src, entry)   \
@@ -110,6 +110,13 @@ static INLINE char world_cull_backface(const world_t *world, const ps1bsp_face_t
     return 1;
 }
 
+static void world_drawface_flat(const world_t *world, const ps1bsp_face_t *face, P_COLOR *color, u_long *ot)
+{
+    // Draw untextured, vertex colored faces, skipping the entire polygon tessellation step
+    const ps1bsp_facevertex_t *faceVertices = &world->faceVertices[face->firstFaceVertex];
+    draw_quadstrip_flat(world->vertices, faceVertices, face->numFaceVertices, color, ot);
+}
+
 static void world_drawface_fast(const world_t *world, const ps1bsp_face_t *face, u_long *ot)
 {
     // Draw untextured, vertex colored faces, skipping the entire polygon tessellation step