Coords are now centre of image rather than top left

5 files changed, 24 insertions, 17 deletions

diff --git a/algorithms/burning-ship.c b/algorithms/burning-ship.c
index 7e27e4b..6f8c9d9 100644
--- a/algorithms/burning-ship.c
+++ b/algorithms/burning-ship.c
@@ -34,17 +34,21 @@ void
 	struct frame *f = &(d->parent_frame);
 	unsigned int x,y,i;
 	double a,b;
+	double left,top;
 	double complex z,c;
 
 	defaultsd(&d->parent_frame.scale, 3.5f);
-	defaultsd(&d->parent_frame.top, -2.2f);
-	defaultsd(&d->parent_frame.left, -2.2f);
+	defaultsd(&d->parent_frame.x, -0.45f);
+	defaultsd(&d->parent_frame.y, -0.45f);
+
+	left = d->parent_frame.x - (d->parent_frame.scale / 2);
+	top = d->parent_frame.y - (d->parent_frame.scale / 2);
 
 	/* FIXME document this */
-	b = clust_id*(f->scale/size)+f->top; /* FIXME document this */
+	b = clust_id*(f->scale/size)+top; /* FIXME document this */
 
 	for (y = clust_id; y < size; y += clust_total) {
-		a = d->core*(f->scale/size)+f->left;
+		a = d->core*(f->scale/size)+left;
 		for (x = d->core; x < size; x += cores) {
 			z = 0;
 			c = a+I*b;
diff --git a/algorithms/mandelbrot.c b/algorithms/mandelbrot.c
index 51d0c43..33d7cde 100644
--- a/algorithms/mandelbrot.c
+++ b/algorithms/mandelbrot.c
@@ -34,18 +34,21 @@ void
 	struct frame *f = &(d->parent_frame);
 	unsigned int x,y,i;
 	double a,b;
+	double left, top;
 	double complex z,c;
 
-	defaultsd(&d->parent_frame.top, -1.75f);
-	defaultsd(&d->parent_frame.left, -2.5f);
 	defaultsd(&d->parent_frame.scale, 3.5f);
+	defaultsd(&d->parent_frame.x, -0.75f);
+	defaultsd(&d->parent_frame.y, 0);
 
+	left = d->parent_frame.x - (d->parent_frame.scale / 2);
+	top = d->parent_frame.y - (d->parent_frame.scale / 2);
 
 	/* FIXME document this */
-	b = clust_id*(f->scale/size)+f->top; /* FIXME document this */
+	b = clust_id*(f->scale/size)+top; /* FIXME document this */
 
 	for (y = clust_id; y < size; y += clust_total) {
-		a = d->core*(f->scale/size)+f->left;
+		a = d->core*(f->scale/size)+left;
 		for (x = d->core; x < size; x += cores) {
 			z = 0;
 			c = a + I*b;
diff --git a/extra/burning-ship-lattice-gen.sh b/extra/burning-ship-lattice-gen.sh
index 1a39c0d..68f483e 100755
--- a/extra/burning-ship-lattice-gen.sh
+++ b/extra/burning-ship-lattice-gen.sh
@@ -1,3 +1,3 @@
 #!/bin/sh
 
-exec ./burning-ship-gen -x -1.8 -y -0.082 -z 0.09 $@
+exec ../burning-ship-gen -x -1.755 -y -0.037 -z 0.09 $@
diff --git a/fractal-gen.c b/fractal-gen.c
index e80c96a..73bd25f 100644
--- a/fractal-gen.c
+++ b/fractal-gen.c
@@ -140,8 +140,8 @@ main(int argc, char **argv)
 		/* FIXME repetition */
 		sections[i].core = i;
 		sections[i].width = width;
-		sections[i].parent_frame.top = f.top;
-		sections[i].parent_frame.left = f.left;
+		sections[i].parent_frame.y = f.y;
+		sections[i].parent_frame.x = f.x;
 		sections[i].parent_frame.scale = f.scale;
 		sections[i].datasize = toalloc;
 		fprintf(stderr, " -> Thread %lu\r", i);
@@ -207,8 +207,8 @@ parse_args(int argc, char **argv)
 	clust_id = 0;
 	clust_total = 1;
 
-	f.left = nan("");
-	f.top = nan("");
+	f.x = nan("");
+	f.y = nan("");
 	f.scale = nan("");
 
 	/* bail out early if no arguments are supplied */
@@ -228,8 +228,8 @@ parse_args(int argc, char **argv)
 			case 'N': clust_id = atoi(optarg); break;
 			case 'T': clust_total = atoi(optarg); break;
 
-			case 'x': f.left = atof(optarg); break;
-			case 'y': f.top = atof(optarg); break;
+			case 'x': f.x = atof(optarg); break;
+			case 'y': f.y = atof(optarg); break;
 			case 'z': f.scale = atof(optarg); break;
 
 			/* redundant case for '?', but explicitness is best */
diff --git a/fractal-gen.h b/fractal-gen.h
index a103d1f..210d50f 100644
--- a/fractal-gen.h
+++ b/fractal-gen.h
@@ -29,8 +29,8 @@
 #include <pthread.h>
 
 struct frame {
-	double top;
-	double left;
+	double x;
+	double y;
 	double scale;
 };