From: Timo Kokkonen <kaapeli@itanic.dy.fi>
Date: Tue, 3 May 2011 19:42:19 +0000 (+0300)
Subject: Increase floating point precision
X-Git-Url: http://git.itanic.dy.fi/?p=mandelbrot;a=commitdiff_plain;h=174797b4eb1de681f5ce369341e838f217254802

Increase floating point precision

Signed-off-by: Timo Kokkonen <kaapeli@itanic.dy.fi>
---

diff --git a/mandelbrot.c b/mandelbrot.c
index 8ce33b9..5dc9aed 100644
--- a/mandelbrot.c
+++ b/mandelbrot.c
@@ -6,10 +6,11 @@
 
 struct context {
 	struct SDL_Surface *screen;
-	double origo_x, origo_y;
+	long double origo_x, origo_y;
 	int motion_x, motion_y;
-	double zoom;
+	long double zoom;
 	int scroll_enabled;
+	int zooms;
 };
 
 static void putpixel(struct SDL_Surface *screen, const int x, const int y,
@@ -26,9 +27,9 @@ static void putpixel(struct SDL_Surface *screen, const int x, const int y,
 
 #define MAX_ITERATION 1000
 
-int get_mandelbrot_iterations(double x0, double y0)
+int get_mandelbrot_iterations(long double x0, long double y0)
 {
-	double x = 0, y = 0, xtemp;
+	long double x = 0, y = 0, xtemp;
 	int iteration = 0;
 
 	while ((x * x + y * y < 2 * 2) && iteration < MAX_ITERATION) {
@@ -43,16 +44,16 @@ int get_mandelbrot_iterations(double x0, double y0)
 	return iteration;
 }
 
-int draw_mandelbrot(struct SDL_Surface *screen, double x1, double x2,
-		double y1, double y2)
+int draw_mandelbrot(struct SDL_Surface *screen, long double x1, long double x2,
+		long double y1, long double y2)
 {
-	double x0, y0, xlen, ylen, xstep, ystep;
+	long double x0, y0, xlen, ylen, xstep, ystep;
 	int iteration, xs, ys;
 
 	xlen = x2 - x1;
 	ylen = y2 - y1;
-	xstep = xlen / (double)screen->w;
-	ystep = ylen / (double)screen->h;
+	xstep = xlen / (long double)screen->w;
+	ystep = ylen / (long double)screen->h;
 
 	y0 = y1;
 #pragma omp parallel for private(xs, ys, x0, y0)
@@ -111,9 +112,11 @@ static int read_events(struct context *ctx)
 		case SDL_MOUSEBUTTONDOWN:
 			if (event.button.button == 4) {
 				ctx->zoom *= 1.5;
-				exit++;
+				ctx->zooms++;
+				delayed_exit++;
 			} else if (event.button.button == 5) {
 				ctx->zoom /= 1.5;
+				ctx->zooms--;
 				delayed_exit++;
 			} else {
 				ctx->scroll_enabled = 1;
@@ -152,7 +155,8 @@ quit:
 
 static void loop(struct context *ctx)
 {
-	double aspect_ratio;
+	long double aspect_ratio;
+	long double x1, x2, y1, y2;
 
 	do {
 		aspect_ratio = ctx->screen->w / ctx->screen->h;
@@ -160,13 +164,13 @@ static void loop(struct context *ctx)
 		ctx->origo_y += ctx->motion_y / ctx->zoom / ctx->screen->h;
 		ctx->motion_x = ctx->motion_y = 0;
 
-		draw_mandelbrot(ctx->screen,
-				ctx->origo_x - aspect_ratio / ctx->zoom,
-				ctx->origo_x + aspect_ratio / ctx->zoom,
-				ctx->origo_y - 1 / ctx->zoom,
-				ctx->origo_y + 1 / ctx->zoom);
+		x1 = ctx->origo_x - aspect_ratio / ctx->zoom;
+		x2 = ctx->origo_x + aspect_ratio / ctx->zoom;
+		y1 = ctx->origo_y - 1 / ctx->zoom;
+		y2 = ctx->origo_y + 1 / ctx->zoom;
 		printf("Drawing area (%f, %f)(%f, %f), zoom %d\n",
-			x1, y1, x2, y2, ctx->zoom );
+			x1, y1, x2, y2, ctx->zooms);
+		draw_mandelbrot(ctx->screen, x1, x2, y1, y2);
 	} while (!read_events(ctx));
 }