Plot arg as hue, norm as value

1 files changed, 23 insertions, 6 deletions

diff --git a/attract.c b/attract.c
index c4cba5c..5ab9aa7 100644
--- a/attract.c
+++ b/attract.c
@@ -19,6 +19,9 @@ const double EPS=1e-1;
 static double complex att_func(double complex x,double exponent){
 	return clog((1-cpow(x,exponent+1))/(1-x));
 
+	// return x;
+	return x*x+CMPLX(-0.2,0.7);
+
 	// return csqrt(M_SQRT2*x);  // sqrt(2) and 0
 	// return csqrt(1+x);  // phi
 	// return csqrt(2*x-1);  // attracts REALLY SLOWLY to 1+0i
@@ -26,20 +29,34 @@ static double complex att_func(double complex x,double exponent){
 	// return clog(x*x);  // "241" basins
 	// return clog(x*x+x);  // 3 basins but intricate structure
 	// return clog(x*x*x*x+x*x*x+x*x+x+1);  // 2 basin fractal?
-	// return csqrt(x*x*x+x*x+x+1);
+	// return csqrt(x*x*x+x*x+x+1);  // lots of nans but really interesting lines
 }
 
 struct colour{
 	unsigned char r,g,b;
 };
 
+static struct colour from_hue(double H){  // H in [0,1]
+	const int C=255;
+	double Hmod=H>=2.0/3 ? H-2.0/3 : H>=1.0/3 ? H-1.0/3 : H;
+	int X=C*(1-fabs(Hmod*6-1));
+	if(H<=1.0/6)return (struct colour){C,X,0};
+	if(H<=2.0/6)return (struct colour){X,C,0};
+	if(H<=3.0/6)return (struct colour){0,C,X};
+	if(H<=4.0/6)return (struct colour){0,X,C};
+	if(H<=5.0/6)return (struct colour){X,0,C};
+	            return (struct colour){C,0,X};
+}
+
 static struct colour make_colour(double complex z){
 	static const double N=3;
 	double norm=cabs(z);
 	if(norm>N)norm=N;
-	int normclr=(int)(norm/N*255);
-	int argclr=(int)((carg(z)+M_PI)/(2*M_PI)*255);
-	return (struct colour){normclr,argclr,0};
+	struct colour clr=from_hue((carg(z)+M_PI)/(2*M_PI));
+	clr.r*=norm/N;
+	clr.g*=norm/N;
+	clr.b*=norm/N;
+	return clr;
 }
 
 struct config{
@@ -115,8 +132,8 @@ static void* thread_entry(void *arg_vp){
 }
 
 int main(int argc,char **argv){
-	const double minx=-3,miny=-3;
-	const double maxx=3,maxy=3;
+	const double minx=-1.5,miny=-1.5;
+	const double maxx=1.5,maxy=1.5;
 	const double width=1000;
 
 	struct config cfg={