Simple-minded floating point dda

1 files changed, 57 insertions, 0 deletions

diff --git a/dda.c b/dda.c
new file mode 100644
index 0000000..fa30f7c
--- /dev/null
+++ b/dda.c
@@ -0,0 +1,57 @@
+#include <stdio.h>
+#include <math.h>
+
+static double
+next_sample_x (double x)
+{
+    return ceil (x - 0.5) + 0.5;
+}
+
+static double
+next_sample_y (double y)
+{
+    return ceil (y - 0.5) + 0.5;
+}
+
+static double
+sample_step_x (double x)
+{
+    (void)x;
+
+    return 1.0;
+}
+
+static double
+sample_step_y (double y)
+{
+    (void)y;
+
+    return 1.0;
+}
+
+static void
+dda (double x0, double y0, double x1, double y1)
+{
+    double y = next_sample_y (y0);
+
+    while (y < next_sample_y (y1))
+    {
+	double x = ((y - y0) / (y1 - y0)) * (x1 - x0) + x0;
+	double xi = next_sample_x (x);
+
+	y += sample_step_y (y);
+    }
+}
+
+int
+main ()
+{
+    dda (0.5, 0.5, 2.5, 1.6);
+    dda (0.3, 0.2, 3.7, 2.2);
+    dda (3.7, 2.2, 7.2, 2.8);
+    dda (3.7, 2.2, 4.2, 7.2);
+    dda (0.5, 0.5, 1.5, 1.5);
+    dda (0.5, 0.5, 2.5, 2.5);
+
+    return 0;
+}