1 files changed, 91 insertions, 0 deletions
diff --git a/julia-c/julia.c b/julia-c/julia.c
new file mode 100644
index 0000000..43e0f91
--- /dev/null
+++ b/julia-c/julia.c
@@ -0,0 +1,91 @@
+#include <stdio.h>
+#include <math.h>
+#include <complex.h>
+#define STB_IMAGE_IMPLEMENTATION
+#include "stb_image.h"
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+#include "stb_image_write.h"
+
+const char *HELP = "julia usage:\n" 
+	"julia <complex num>[a+bj] <resolution>[integer] <depth>[integer] <bounds>[x-,x+,y-,y+]\n"
+	"\n"
+	"\tcomplex_num: a complex number in the form a + bj where j is the "
+	"imaginary unit.\n"
+	"\tresolution: resolution (in pixels) of the image\n"
+	"\tdepth: iteration count for the julia function, warning: slow at high values >100\n"
+	"\tbounds: the bounds of the graphs as a comma separated list without spaces "
+	"in the form: minX,maxX,minY,maxY.\n"
+	"\tBounds above 2 are generally not interesting.\n"
+	"\n"
+	"All arguments are required. This command prints bitmap directly to stdout which is "
+	"(probably) not what you want. You should always pipe the output somewhere like:\n"
+	"julia 1+1j 300 -1,1,-1,1 > file.bmp";
+const int RGB_MODE = 3; // don't care about transparency, so we go for 8 bit channel
+
+int julia(double complex z, double complex c, int d) {
+	// z: coordinate
+	// c: complex seed
+	// d: depth, iteration count
+	int ic = 0; // iteration count
+	while(ic < d){
+		if(cabs(z) > 2)
+		       break;
+		z = z * z + c;
+		ic++;	
+	}
+	return ic;
+}
+
+int write_image(double complex seed, int r, int depth, float bounds[4]) {
+	float x, y;
+	int pixels = r * r;
+	int cur_pixel = 3 * pixels - 1;
+	char const *filename = "/dev/stdout";
+	// In a bitmap: 3 bytes makes a pixel (RGB)
+	uint8_t *img_data = (uint8_t *) STBI_MALLOC(pixels * 3 * sizeof(uint8_t));
+	// In this image library, data is stored in a 
+	// 1-D array separated by row, so you need to fill
+	// the pixels horizontally first
+	
+	float dx = bounds[1] - bounds[0];
+	float dy = bounds[3] - bounds[2];
+	if (dx <= 0 || dy <= 0)
+		return 0; // failure (to match stbi_write)	
+
+	for(y = bounds[2]; y < bounds[3]; y += dy/((float) r - 1)) {
+		for(x = bounds[0]; x < bounds[1]; x += dx/((float) r - 1)) {
+			double complex z = x + y * I;
+			int out = julia(z, seed, depth);
+			img_data[cur_pixel - 2] = out % 32 * 8;
+			img_data[cur_pixel - 1] = out % 16 * 16;
+			img_data[cur_pixel] = out % 8 * 32;
+			cur_pixel -= 3;	
+		}
+	}
+	// returns 0 on failure	
+	return stbi_write_bmp(filename, r, r, RGB_MODE, img_data);
+}
+
+int main(int argc, char *argv[]) {
+	double complex seed;
+	int res, depth;
+	float b[4];
+	
+	if(argc != 5) {
+		printf("%s\n", HELP);
+		return 1;
+	}
+	else {
+		float re, img;
+		sscanf(argv[1], "%f+%fj", &re, &img);
+		sscanf(argv[2], "%d", &res);
+		sscanf(argv[3], "%d", &depth);
+		sscanf(argv[4], "%f,%f,%f,%f", &b[0], &b[1], &b[2], &b[3]);
+		seed = re + img * I;
+		if (!write_image(seed, res, depth, b)) {
+			printf("Error in arguments, could not make image\n");
+			return 1;
+		}
+	}
+	return 0;
+}