From 89adaad118d714200f5dd986016ece26d6334c20 Mon Sep 17 00:00:00 2001
From: Timo Kokkonen <kaapeli@itanic.dy.fi>
Date: Tue, 13 Apr 2010 20:18:11 +0300
Subject: [PATCH] draw_planet: Separate circle drawing into its own function

It is easier to draw circles elsewhere in the code if the circle
drawing is separated.

Signed-off-by: Timo Kokkonen <kaapeli@itanic.dy.fi>
---
 planet.c | 66 +++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 42 insertions(+), 24 deletions(-)

diff --git a/planet.c b/planet.c
index 7f39cb6..88577ee 100644
--- a/planet.c
+++ b/planet.c
@@ -94,50 +94,68 @@ void create_planets(struct planet *p, int num, double total_mass, double radius)
 	}
 }
 
-void draw_planet(SDL_Surface *screen, struct planet *p,
-		 const struct camera *cam)
+void draw_circle(SDL_Surface *screen, const struct vector *pos,
+		 const double radius,
+		 char r, char g, char b, int transparent)
 {
-	struct vector pos;
-	float radius = p->radius * cam->zoom;
-	float r2 = radius * radius;
 	int x, x_start, y, x_end;
+	float r2 = radius * radius;
 
-	vector_sub(&p->pos, &cam->pos, &pos);
-	vector_scale(&pos, cam->zoom, &pos);
-	pos.x += screen->w / 2;
-	pos.y += screen->h / 2;
-
-	y = MAX(pos.y - radius, 0);
+	y = MAX(pos->y - radius, 0);
 
 	if (radius * 2 <= 1) {
-		if (pos.x >= 0 && pos.x < screen->w &&
-		    pos.y >= 0 && pos.y < screen->h)
-			putpixel(screen, (int)pos.x, (int)pos.y,
-				 p->r, p->g, p->b);
+		if (pos->x >= 0 && pos->x < screen->w &&
+		    pos->y >= 0 && pos->y < screen->h)
+			putpixel(screen, (int)pos->x, (int)pos->y,
+				 r, g, b);
 		return;
 	}
 
-	for (; y < MIN(pos.y + radius, screen->h); y++) {
+	for (; y < MIN(pos->y + radius, screen->h); y++) {
 		int offset;
 		unsigned char *buf = screen->pixels;
-		float y2 = (y - pos.y);
+		float y2 = (y - pos->y);
 
 		y2 = sqrt(r2 - y2 * y2);
-		x_start = pos.x - y2;
-		x_end = pos.x + y2;
+		x_start = pos->x - y2;
+		x_end = pos->x + y2;
 		x_start = MAX(0, x_start);
 		x_end = MIN(x_end, screen->w);
 
 		offset = y * screen->pitch + x_start * 4;
-		for (x = x_start; x < x_end; x++) {
-			buf[offset++] = p->b;
-			buf[offset++] = p->g;
-			buf[offset++] = p->r;
-			offset++;
+		if (transparent) {
+			for (x = x_start; x < x_end; x++) {
+				buf[offset++] += b;
+				buf[offset++] += g;
+				buf[offset++] += r;
+				offset++;
+			}
+		} else {
+			for (x = x_start; x < x_end; x++) {
+				buf[offset++] = b;
+				buf[offset++] = g;
+				buf[offset++] = r;
+				offset++;
+			}
 		}
 	}
 }
 
+void draw_planet(SDL_Surface *screen, struct planet *p,
+		 const struct camera *cam)
+{
+	struct vector pos;
+	float radius = p->radius * cam->zoom;
+	int i;
+
+	vector_sub(&p->pos, &cam->pos, &pos);
+	vector_scale(&pos, cam->zoom, &pos);
+	pos.x += screen->w / 2;
+	pos.y += screen->h / 2;
+
+	draw_circle(screen, &pos, radius, p->r, p->g, p->b, 0);
+}
+
 int gravitize_planets(struct planet *a, struct planet *b, const double time)
 {
 	struct vector distance, sum;
-- 
2.45.0