Add lightcone

Makefile

@@ -15,7 +15,6 @@ EXAMPLES = \
 	example/basic \
 	example/riemman \
 	example/n-cube \
-	example/n-hilbert-cube \
 	example/light-cone \
 	example/lens
 

example/light-cone.c

@@ -0,0 +1,51 @@
+#include <math.h>
+#include <stdio.h>
+
+#define KLEIN_IMPLEMENT
+#include <klein/klein.h>
+#include <klein/norm.h>
+#include <klein/parm.h>
+
+void lightcone(float *d_surface, int *coord, unsigned char * grid)
+{
+
+	const int n = 3;
+	float norm = 0;
+	float sphere[4];
+
+	for (int i = 0; i < n; i++)
+		sphere[i] = ((float)coord[i] / grid[i]) - 0.5;
+
+	for(int i = 0; i < n; i++)
+		norm += sphere[i] * sphere[i];
+
+	for (int i = 0; i < n; i++)
+		sphere[i] = sphere[i] / sqrt(norm);
+	
+	float d =  ((float)coord[3]/grid[3]) ;
+	d_surface[0] = d* sphere[0];
+	d_surface[1] = d* sphere[1];
+	d_surface[2] = d* sphere[2];
+	d_surface[3] = d;
+}
+
+int main(void)
+{
+	char * file_name = "lightcone";
+	struct klein klein;
+	struct parm parametrization = {
+		.grid = (unsigned char[]){8, 8,8,8},
+		.m = 4,
+		.n = 4,
+		.f = lightcone,
+	};
+
+
+	klein_parametrize(&klein, parametrization);
+	klein_normalize(&klein);
+	klein_export_file(klein, file_name);
+
+	free(klein.vertex);
+	free(klein.normals);
+	return 0;
+}