Histogram plus gradients

2 files changed, 116 insertions, 14 deletions

diff --git a/bluenoise.c b/bluenoise.c
index 25ab43a..5d0b4c1 100644
--- a/bluenoise.c
+++ b/bluenoise.c
@@ -2,10 +2,11 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <math.h>
+#include <string.h>
 
 #include "fft.h"
 
-#define N_SAMPLES 128
+#define N_SAMPLES 512
 
 #define K   ((2 * M_PI) / N_SAMPLES)
 
@@ -34,8 +35,12 @@ main ()
     {
 	for (j = 0; j < N_SAMPLES; ++j)
 	{
-	    noise[i * N_SAMPLES + j].re = 0.5 * (drand48() + drand48());
+#if 0
+	    noise[i * N_SAMPLES + j].re = 0.6 * (drand48() + drand48()) - 0.2 * drand48();
+#endif
 	    noise[i * N_SAMPLES + j].im = 0;
+	    noise[i * N_SAMPLES + j].re = 0.5 * (drand48() + drand48());
+	    noise[i * N_SAMPLES + j].re = 0.6 * (drand48() + drand48()) - 0.2 * drand48();
 	}
     }
 
@@ -57,27 +62,84 @@ main ()
 
 	    if (d != 0.0)
 	    {
-		noise[i * N_SAMPLES + j].re *= 0.5 * (cos (M_PI * (1 - 2 * f)) + 1.0);
-		noise[i * N_SAMPLES + j].im *= 0.5 * (cos (M_PI * (1 - 2 * f)) + 1.0);
-		    
+		double factor = 0;
+
+#define CHECK(n)							\
+		((i <= (n) || i >= N_SAMPLES - ((n) + 1))  ^		\
+		 (j <= (n) || j >= N_SAMPLES - ((n) + 1)))
+		
+#if 0
+		if (CHECK(1))
+		{
+		    factor = 1;
+		}
+		else if (CHECK(42))
+		{
+		    factor = 1;
+		}
+		else
+		{
+		    factor = 0.1;
+		}
+#endif
+		if (f <= 0.5)
+		{
+		    factor = 0.5 * (cos (M_PI * (1 - 2 * (f))) + 1.0);
+		}
+		else
+		{
+		    factor = 1;
+		}
 #if 0
 		noise[i * N_SAMPLES + j].re *= 2.4 * f;
 		noise[i * N_SAMPLES + j].im *= 2.4 * f;
 #endif
+#if 0
+		if (f < 0.4)
+		    factor = 0;
+		else
+		    factor = 12 * (f - 0.4);
+#endif
+
+		noise[i * N_SAMPLES + j].re *= factor;
+		noise[i * N_SAMPLES + j].im *= factor; // 8 * N_SAMPLES * N_SAMPLES * factor;
 	    }
 	}
     }
 
     printf ("%f %f\n", noise[i * (N_SAMPLES/2) + N_SAMPLES/2].re, noise[i * (N_SAMPLES/2) + N_SAMPLES/2].im);
     
-#if 0
-    noise[i * (N_SAMPLES / 2) + N_SAMPLES / 2].re = 1.5;
-    noise[i * (N_SAMPLES / 2) + N_SAMPLES / 2].im = 0;
-#endif
-
     shift_2d (noise, N_SAMPLES);
     
     ifft_2d (noise, N_SAMPLES);
+
+#define N_BUCKETS  128
+    
+    int hist[N_BUCKETS];
+    int bad;
+    bad = 0;
+    memset (hist, 0, sizeof hist);
+    for (i = 0; i < N_SAMPLES * N_SAMPLES; ++i)
+    {
+	int v = (noise[i].re * N_BUCKETS);
+	if (v == N_BUCKETS)
+	    v = N_BUCKETS - 1;
+	else if (v >= N_BUCKETS || v < 0)
+	{
+	    printf ("bad: %f (%d)\n", noise[i].re, v);
+	    bad++;
+	}
+	else
+	    hist[v]++;
+    }
+    int total = 0;
+    for (i = 0; i < N_BUCKETS; ++i)
+    {
+	printf ("%d: %d\n", i, hist[i]);
+	total += hist[i];
+    }
+    printf ("bad: %d (%f %%)\n", bad, 100.0 * bad / (N_SAMPLES * N_SAMPLES));
+    printf ("total: %d \n", total + bad);
     
     show_image ("blue noise", noise, N_SAMPLES);
     
diff --git a/gtk-utils.c b/gtk-utils.c
index e1eca8d..e8a8d63 100644
--- a/gtk-utils.c
+++ b/gtk-utils.c
@@ -15,9 +15,11 @@ pixbuf_from_buffer (complex_t *buffer, int n)
     {
 	for (w = 0; w < n; ++w)
 	{
-	    char *pb = (char *)p_bits;
+	    unsigned char *pb = (unsigned char *)p_bits;
 	    complex_t c = buffer[h * n + w];
 	    double v;
+	    int vi;
+	    int g;
 
 	    pb += h * p_stride + w * 4;
 
@@ -26,11 +28,49 @@ pixbuf_from_buffer (complex_t *buffer, int n)
 		v = 255.0;
 	    if (v < 0)
 		v = 0;
+
+#if 0
+	    vi *= 0x0f;
+#endif
+
+#define SADD(v,a)   (((v) + (a) > 0xff)? 0xff : ((v) + (a) < 0)? 0 : ((v) + (a)))
+	    
+	    g = ((double)h / n) * 255;
+
+#if 0
+	    if (vi + g > 0xff)
+		pb[0] = pb[1] = pb[2] = 0xff;
+	    else
+		pb[0] = pb[1] = pb[2] = 0x00;
+#endif
+	    vi = (v - 0x80);
+	    vi >>= 5;
+
+	    int rr, gg, bb;
+
+	    rr = 0x3;
+	    gg = 0x80 - 0x80/255.0 * g;
+	    bb = 0x3;
 	    
-	    pb[0] = (int)(v);
-	    pb[1] = (int)(v);
-	    pb[2] = (int)(v);
+	    pb[0] = SADD (rr, vi);
+	    pb[1] = SADD (gg, - vi);
+	    pb[2] = SADD (bb, vi);
+	    pb[3] = 0xff;
+
+	    pb[0] = rr;
+	    pb[1] = gg;
+	    pb[2] = bb;
 	    pb[3] = 0xff;
+
+#define TRUNC(x, n)							\
+	    x >>= (8 - n);						\
+	    x <<= (8 - n);						\
+	    x |= x >> n;						\
+	    x |= x >> (2 * n)
+
+	    TRUNC(pb[0], 8);
+	    TRUNC(pb[1], 8);
+	    TRUNC(pb[2], 8);
 	}
     }