From c3bdd9d7db403c15bbef4b1d6aa0eedd5f0be72e Mon Sep 17 00:00:00 2001
From: div0 <div0@f962a42d-fe04-0410-a3ab-8c8b0445ebaa>
Date: Wed, 30 Jul 2008 16:05:50 +0000
Subject: [PATCH] start of a bright spot finder for skyboxes

git-svn-id: svn://svn.icculus.org/nexuiz/trunk@3982 f962a42d-fe04-0410-a3ab-8c8b0445ebaa
---
 misc/brightspot.c | 140 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 140 insertions(+)
 create mode 100644 misc/brightspot.c

diff --git a/misc/brightspot.c b/misc/brightspot.c
new file mode 100644
index 000000000..8e322948c
--- /dev/null
+++ b/misc/brightspot.c
@@ -0,0 +1,140 @@
+#include <stdio.h>
+#include <math.h>
+
+// USAGE:
+//   for X in *.tga; do convert "$X" -geometry 512x512 -depth 8 GRAY:-; done > /tmp/foo
+//   brightspot /tmp/foo
+// It should output the right parameters for the sun direction in q3map2's format.
+// But probably is broken.
+
+#define false 0
+#define true 1
+
+int sides_alphabet[6] =
+{
+	2, // bk
+	5, // dn
+	3, // ft
+	1, // lf
+	0, // rt
+	4  // up
+};
+
+int flip[6*3] =
+{
+	false, false,  true, // "rt"
+	 true,  true,  true, // "lf"
+	false,  true, false, // "bk"
+	 true, false, false, // "ft"
+	false, false,  true, // "up"
+	false, false,  true  // "dn"
+};
+
+static const double skyboxvertex3f[6*4*3] =
+{
+        // skyside[0]
+         16, -16,  16,
+         16, -16, -16,
+         16,  16, -16,
+         16,  16,  16,
+        // skyside[1]
+        -16,  16,  16,
+        -16,  16, -16,
+        -16, -16, -16,
+        -16, -16,  16,
+        // skyside[2]
+         16,  16,  16,
+         16,  16, -16,
+        -16,  16, -16,
+        -16,  16,  16,
+        // skyside[3]
+        -16, -16,  16,
+        -16, -16, -16,
+         16, -16, -16,
+         16, -16,  16,
+        // skyside[4]
+        -16, -16,  16,
+         16, -16,  16,
+         16,  16,  16,
+        -16,  16,  16,
+        // skyside[5]
+         16, -16, -16,
+        -16, -16, -16,
+        -16,  16, -16,
+         16,  16, -16
+};
+
+void MapCoord(int pic, int x, int y, double vec[3])
+{
+	int h;
+	int flipx = flip[3*pic+0];
+	int flipy = flip[3*pic+1];
+	int flipdiag = flip[3*pic+2];
+
+	double a[3] = { skyboxvertex3f[pic*4*3+0*3+0], skyboxvertex3f[pic*4*3+0*3+1], skyboxvertex3f[pic*4*3+0*3+2] };
+	double b[3] = { skyboxvertex3f[pic*4*3+1*3+0], skyboxvertex3f[pic*4*3+1*3+1], skyboxvertex3f[pic*4*3+1*3+2] };
+	double c[3] = { skyboxvertex3f[pic*4*3+2*3+0], skyboxvertex3f[pic*4*3+2*3+1], skyboxvertex3f[pic*4*3+2*3+2] };
+	//double d[3] = { skyboxvertex3f[pic*4*3+3*3+0], skyboxvertex3f[pic*4*3+3*3+1], skyboxvertex3f[pic*4*3+3*3+2] };
+
+	if(flipx)
+	{
+		x = 511 - x;
+	}
+
+	if(flipy)
+	{
+		y = 511 - y;
+	}
+
+	if(flipdiag)
+	{
+		h = x; x = y; y = h;
+	}
+
+	vec[0] = a[0] + (b[0] - a[0]) * (x + 0.5) / 512.0 + (c[0] - b[0]) * (y + 0.5) / 512.0;
+	vec[1] = a[1] + (b[1] - a[1]) * (x + 0.5) / 512.0 + (c[1] - b[1]) * (y + 0.5) / 512.0;
+	vec[2] = a[2] + (b[2] - a[2]) * (x + 0.5) / 512.0 + (c[2] - b[2]) * (y + 0.5) / 512.0;
+}
+
+int main(int argc, char **argv)
+{
+	FILE *f;
+	int i, j, k;
+	unsigned char picture[6][512][512];
+	double brightvec[3];
+	double pitch, yaw;
+
+	if(argc != 2)
+	{
+		fprintf(stderr, "Usage: %s imagefile.gray\n", *argv);
+		return 1;
+	}
+
+	f = fopen(argv[1], "rb");
+	if(!f)
+	{
+		perror("fopen");
+		return 1;
+	}
+	fread(&picture, sizeof(picture), 1, f);
+	fclose(f);
+
+	brightvec[0] = brightvec[1] = brightvec[2] = 0;
+	for(i = 0; i < 6; ++i)
+		for(j = 0; j < 512; ++j)
+			for(k = 0; k < 512; ++k)
+			{
+				double vec[3], f;
+				MapCoord(i, j, k, vec);
+				f = exp(10 * (picture[i][j][k] - 255)) / sqrt(vec[0]*vec[0] + vec[1]*vec[1] + vec[2]*vec[2]);
+				brightvec[0] += f * vec[0];
+				brightvec[1] += f * vec[1];
+				brightvec[2] += f * vec[2];
+			}
+	
+	pitch = -atan2(brightvec[2], sqrt(brightvec[0]*brightvec[0] + brightvec[1]*brightvec[1]));
+	yaw = atan2(brightvec[1], brightvec[0]);
+
+	printf("%f %f\n", yaw * 180 / M_PI, pitch * 180 / M_PI);
+	return 0;
+}
-- 
2.39.2