From bd0f3345a938b35ce6a12f6150373b0955b8dd12 Mon Sep 17 00:00:00 2001
From: Timothy Pearson <kb9vqf@pearsoncomputing.net>
Date: Sun, 10 Jul 2011 15:24:15 -0500
Subject: Add Qt3 development HEAD version

---
 examples/demo/opengl/fbm.c | 207 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 207 insertions(+)
 create mode 100644 examples/demo/opengl/fbm.c

(limited to 'examples/demo/opengl/fbm.c')

diff --git a/examples/demo/opengl/fbm.c b/examples/demo/opengl/fbm.c
new file mode 100644
index 0000000..47d5a61
--- /dev/null
+++ b/examples/demo/opengl/fbm.c
@@ -0,0 +1,207 @@
+/*****************************************************************
+
+  Implementation of the fractional Brownian motion algorithm. These
+  functions were originally the work of F. Kenton Musgrave.
+  For documentation of the different functions please refer to the
+  book: 
+  "Texturing and modeling: a procedural approach"
+  by David S. Ebert et. al.
+
+******************************************************************/
+
+#if defined (_MSC_VER)
+#include <qglobal.h>
+#endif
+
+#include <time.h>
+#include <stdlib.h>
+#include "fbm.h"
+
+#if defined(Q_CC_MSVC)
+#pragma warning(disable:4244)
+#endif
+
+/* Definitions used by the noise2() functions */
+
+#define B 0x100
+#define BM 0xff
+
+#define N 0x1000
+#define NP 12   /* 2^N */
+#define NM 0xfff
+
+static int   p[B + B + 2];
+static float g3[B + B + 2][3];
+static float g2[B + B + 2][2];
+static float g1[B + B + 2];
+static int   start = 1;
+
+static void init(void);
+
+#define s_curve(t) ( t * t * (3. - 2. * t) )
+
+#define lerp(t, a, b) ( a + t * (b - a) )
+
+#define setup(i,b0,b1,r0,r1)\
+	t = vec[i] + N;\
+	b0 = ((int)t) & BM;\
+	b1 = (b0+1) & BM;\
+	r0 = t - (int)t;\
+	r1 = r0 - 1.;
+#define at3(rx,ry,rz) ( rx * q[0] + ry * q[1] + rz * q[2] )
+
+static float noise3(float vec[3]);
+
+/* Fractional Brownian Motion function */
+
+double fBm( Vector point, double H, double lacunarity, double octaves,
+	    int init )
+{
+
+    double            value, frequency, remainder;
+    int               i;
+    static double     exponent_array[10];
+    float             vec[3];
+
+    /* precompute and store spectral weights */
+    if ( init ) {
+	start = 1;
+	srand( time(0) );
+	/* seize required memory for exponent_array */
+	frequency = 1.0;
+	for (i=0; i<=octaves; i++) {
+	    /* compute weight for each frequency */
+	    exponent_array[i] = pow( frequency, -H );
+	    frequency *= lacunarity;
+	}
+    }
+
+    value = 0.0;            /* initialize vars to proper values */
+    frequency = 1.0;
+    vec[0]=point.x;
+    vec[1]=point.y;
+    vec[2]=point.z;
+
+
+    /* inner loop of spectral construction */
+    for (i=0; i<octaves; i++) {
+	/* value += noise3( vec ) * exponent_array[i];*/
+	value += noise3( vec ) * exponent_array[i];
+	vec[0] *= lacunarity;
+	vec[1] *= lacunarity;
+	vec[2] *= lacunarity;
+    } /* for */
+
+    remainder = octaves - (int)octaves;
+    if ( remainder )      /* add in ``octaves''  remainder */
+	/* ``i''  and spatial freq. are preset in loop above */
+	value += remainder * noise3( vec ) * exponent_array[i];
+
+    return( value );
+
+} /* fBm() */
+
+
+float noise3(float vec[3])
+{
+    int bx0, bx1, by0, by1, bz0, bz1, b00, b10, b01, b11;
+    float rx0, rx1, ry0, ry1, rz0, rz1, *q, sy, sz, a, b, c, d, t, u, v;
+    register int i, j;
+
+    if (start) {
+	start = 0;
+	init();
+    }
+
+    setup(0, bx0,bx1, rx0,rx1);
+    setup(1, by0,by1, ry0,ry1);
+    setup(2, bz0,bz1, rz0,rz1);
+
+    i = p[ bx0 ];
+    j = p[ bx1 ];
+
+    b00 = p[ i + by0 ];
+    b10 = p[ j + by0 ];
+    b01 = p[ i + by1 ];
+    b11 = p[ j + by1 ];
+
+    t  = s_curve(rx0);
+    sy = s_curve(ry0);
+    sz = s_curve(rz0);
+
+
+    q = g3[ b00 + bz0 ] ; u = at3(rx0,ry0,rz0);
+    q = g3[ b10 + bz0 ] ; v = at3(rx1,ry0,rz0);
+    a = lerp(t, u, v);
+
+    q = g3[ b01 + bz0 ] ; u = at3(rx0,ry1,rz0);
+    q = g3[ b11 + bz0 ] ; v = at3(rx1,ry1,rz0);
+    b = lerp(t, u, v);
+
+    c = lerp(sy, a, b);
+
+    q = g3[ b00 + bz1 ] ; u = at3(rx0,ry0,rz1);
+    q = g3[ b10 + bz1 ] ; v = at3(rx1,ry0,rz1);
+    a = lerp(t, u, v);
+
+    q = g3[ b01 + bz1 ] ; u = at3(rx0,ry1,rz1);
+    q = g3[ b11 + bz1 ] ; v = at3(rx1,ry1,rz1);
+    b = lerp(t, u, v);
+
+    d = lerp(sy, a, b);
+
+    return lerp(sz, c, d);
+}
+
+static void normalize2(float v[2])
+{
+    float s;
+
+    s = sqrt(v[0] * v[0] + v[1] * v[1]);
+    v[0] = v[0] / s;
+    v[1] = v[1] / s;
+}
+
+static void normalize3(float v[3])
+{
+    float s;
+
+    s = sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]);
+    v[0] = v[0] / s;
+    v[1] = v[1] / s;
+    v[2] = v[2] / s;
+}
+
+static void init(void)
+{
+    int i, j, k;
+    
+    for (i = 0 ; i < B ; i++) {
+	p[i] = i;
+
+	g1[i] = (float)((rand() % (B + B)) - B) / B;
+
+	for (j = 0 ; j < 2 ; j++)
+	    g2[i][j] = (float)((rand() % (B + B)) - B) / B;
+	normalize2(g2[i]);
+
+	for (j = 0 ; j < 3 ; j++)
+	    g3[i][j] = (float)((rand() % (B + B)) - B) / B;
+	normalize3(g3[i]);
+    }
+
+    while (--i) {
+	k = p[i];
+	p[i] = p[j = rand() % B];
+	p[j] = k;
+    }
+
+    for (i = 0 ; i < B + 2 ; i++) {
+	p[B + i] = p[i];
+	g1[B + i] = g1[i];
+	for (j = 0 ; j < 2 ; j++)
+	    g2[B + i][j] = g2[i][j];
+	for (j = 0 ; j < 3 ; j++)
+	    g3[B + i][j] = g3[i][j];
+    }
+}
-- 
cgit v1.2.3