From e6f8a3356a91e0304e9965c7b8bfc2f06a2b79cc Mon Sep 17 00:00:00 2001
From: quou <quou@disroot.org>
Date: Sat, 6 Jul 2024 17:55:46 +1000
Subject: Triangle fill.

---
 render.c | 133 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 130 insertions(+), 3 deletions(-)

(limited to 'render.c')

diff --git a/render.c b/render.c
index 74da997..5949ee9 100644
--- a/render.c
+++ b/render.c
@@ -1,3 +1,5 @@
+#include "maths.h"
+#include "plat.h"
 #include "render.h"
 
 static int font_w = 960;
@@ -121,10 +123,11 @@ Colour blend_mod(Colour dst, Colour src, Colour mod) {
 }
 
 
-void ren_begin(Renderer* r, Colour* t, int w, int h) {
+void ren_begin(Renderer* r, Colour* t, int* d, int w, int h) {
 	r->t = t;
 	r->w = w;
 	r->h = h;
+	r->d = d;
 	r->clip.x = 0;
 	r->clip.y = 0;
 	r->clip.w = w;
@@ -149,6 +152,13 @@ void ren_clearc(Renderer* r, Colour c) {
 		*d = c;
 }
 
+void ren_cleard(Renderer* r, int depth) {
+	int* d = r->d;
+	int i = 0, e = r->w * r->h;
+	for (i = 0; i < e; i++, d++)
+		*d = depth;
+}
+
 void ren_clip(Renderer* r, const Rect* c) {
 	r->clip = *c;
 }
@@ -183,8 +193,8 @@ void ren_char(
 	for (j = re.y, l = sub.y; j < ey; j++, l++) {
 		for (i = re.x, k = sub.x; i < ex; i++, k++) {
 			int si = k + l * font_w;
-			unsigned bits = font_data[si / 32];
-			int bit = bits & (1 << si % 32);
+			unsigned bits = font_data[si >> 5];
+			int bit = bits & 1 << (si & 0x1f);
 			if (bit)
 				*dst = blend(*dst, c);
 			dst++;
@@ -205,3 +215,120 @@ void ren_text(
 		ren_char(r, c, x, y, *s);
 }
 
+#define max_tri_ec 2
+
+void swap_vert(int* a, int* b, int ec) {
+	int t, i;
+	for (i = 0; i < ec; i++) {
+		t = a[i];
+		a[i] = b[i];
+		b[i] = t;
+	}
+}
+
+int tri_hand(int* v0, int* v1, int* v2) {
+	return
+		(v1[0] - v0[0]) * (v2[1] - v0[1]) -
+		(v2[0] - v0[0]) * (v1[1] - v0[1]) > 0;
+}
+
+void ren_tri(
+	Renderer* r,
+	Colour c,
+	int* v0,
+	int* v1,
+	int* v2,
+	Tri_Mode mode
+) {
+	int ec, sx, ex, x, y, me, ms, e, ha;
+	int sb = 0, * d;
+	switch (mode) {
+		case tri_mode_flat:
+			ec = 2;
+			break;
+		default: assert(0);
+	}
+	if (v0[1] > v1[1])
+		swap_vert(v0, v1, ec);
+	if (v1[1] > v2[1])
+		swap_vert(v1, v2, ec);
+	if (v0[1] > v1[1])
+		swap_vert(v0, v1, ec);
+	ha = tri_hand(v0, v1, v2);
+	sb = v1[1] == v2[1];
+	if (v0[1] == v1[1]) goto rb;
+	if (ha) {
+		ms =
+			((v2[0] - v0[0]) << fbits) /
+			(v2[1] - v0[1]);
+		me =
+			((v1[0] - v0[0]) << fbits) /
+			(v1[1] - v0[1]);
+		sx = v0[0] << fbits;
+		ex = v0[0] << fbits;
+	} else {
+		ms =
+			((v1[0] - v0[0]) << fbits) /
+			(v1[1] - v0[1]);
+		me =
+			((v2[0] - v0[0]) << fbits) /
+			(v2[1] - v0[1]);
+		sx = v0[0] << fbits;
+		ex = v0[0] << fbits;
+	}
+	for (
+		y  = v0[1];
+		y <= v1[1];
+		y++, sx += ms, ex += me
+	) for (
+			x = sx >> fbits,
+			e = ex >> fbits;
+			x < e;
+			x++
+		) {
+			d = &r->d[x + y * r->w];
+			if (*d > v0[2]) {
+				*d = v0[2];
+				r->t[x + y * r->w] = c;
+			}
+		}
+rb:
+	if (sb) return;
+	if (ha) {
+		ms = ((v2[0] - v0[0]) << fbits) /
+			(v2[1] - v0[1]);
+		me =
+			((v2[0] - v1[0]) << fbits) /
+			(v2[1] - v1[1]);
+		sx =
+			(v0[0] << fbits) + (v1[1] - v0[1]) * ms + 1;
+		ex = v1[0] << fbits;
+	} else {
+		me =
+			((v2[0] - v0[0]) << fbits) /
+			(v2[1] - v0[1]);
+		ms = 
+			((v2[0] - v1[0]) << fbits) /
+			(v2[1] - v1[1]);
+		sx = v1[0] << fbits;
+		ex =
+			(v0[0] << fbits) + (v1[1] - v0[1]) * me + 1;
+	}
+	for (
+		y = v1[1];
+		y <= v2[1];
+		y++, sx += ms, ex += me
+	) for (
+			x = sx >> fbits,
+			e = ex >> fbits;
+			x < e;
+			x++
+		) {
+			d = &r->d[x + y * r->w];
+			if (*d > v0[2]) {
+				*d = v0[2];
+				r->t[x + y * r->w] = c;
+			}
+		}
+}
+
-- 
cgit v1.2.3-54-g00ecf