mandelbrot

commit 83169cdcb60716016e096d5433cd7de1beacf26b
parent c53860987a368f8e2f80c722c7b0bd48631e69f9
Author: Mikołaj Lenczewski <mblenczewski@gmail.com>
Date:   Sun, 19 Jan 2025 12:50:22 +0000

Implement hsv smooth colouring

Diffstat:
M
src/main.c
 | 
51
+++++++++++++++++++++++++++++++++++++++++----------
M
src/mandelbrot.h
 | 
1
+

2 files changed, 42 insertions(+), 10 deletions(-)
diff --git a/src/main.c b/src/main.c
@@ -16,7 +16,7 @@ static void
 usage(char *prog)
 {
 	fprintf(stderr, "Usage: %s [-hv] [-r <xres>x<yres> ] [-i <maxiters>] "
-			"[-p mono|gray|hist|smooth ] [-o <out.bmp>]\n",
+			"[-p basic|mono|gray|hist|smooth ] [-o <out.bmp>]\n",
 			prog);
 
 	fprintf(stderr, "\t-h : display help information\n");
@@ -66,7 +66,9 @@ parse_opts(int argc, char **argv, struct opts *opts)
 			  break;
 
 		case 'p':
-			  if (strcmp(optarg, "mono") == 0) {
+			  if (strcmp(optarg, "basic") == 0) {
+				  opts->palette = PALETTE_BASIC;
+			  } else if (strcmp(optarg, "mono") == 0) {
 				  opts->palette = PALETTE_MONOCHROME;
 			  } else if (strcmp(optarg, "gray") == 0) {
 				  opts->palette = PALETTE_GRAYSCALE;
@@ -139,32 +141,61 @@ point(float x, float y, uint32_t max_iters, float *out)
 #define CLAMP(v, v0, v1) MIN(MAX((v), (v0)), (v1))
 
 static inline uint32_t
+hsv_to_rgb(float hue, float sat, float val)
+{
+	float h = fmodf(hue, 360.0);
+
+	float hp = h / 60.0;
+	float c = val * sat;
+	float x = c * (1 - fabsf(fmodf(hp, 2.0) - 1));
+
+	float rgb[3] = {0};
+
+	if (0 <= hp && hp < 1)      { rgb[0] = c; rgb[1] = x; }
+	else if (1 <= hp && hp < 2) { rgb[0] = x; rgb[1] = c; }
+	else if (2 <= hp && hp < 3) { rgb[1] = c; rgb[2] = x; }
+	else if (3 <= hp && hp < 4) { rgb[1] = x; rgb[2] = c; }
+	else if (4 <= hp && hp < 5) { rgb[0] = x; rgb[2] = c; }
+	else if (5 <= hp && hp < 6) { rgb[0] = c; rgb[2] = x; }
+
+	float m = val - c;
+	rgb[0] += m;
+	rgb[1] += m;
+	rgb[2] += m;
+
+	return pixel(rgb[0] * 255, rgb[1] * 255, rgb[2] * 255, 255);
+}
+
+static inline uint32_t
 palette(float abs2, uint32_t iters, uint32_t max_iters, enum palette_type type)
 {
 	float f = (float) iters / max_iters;
+	float smooth_iters = (iters + 1) - (logf(logf(sqrtf(abs2))) / M_LN2);
+	float sf = CLAMP(smooth_iters / max_iters, 0.0f, 1.0f);
+	float v = 255 * (1 - sf);
 
 	switch (type) {
-	case PALETTE_MONOCHROME:
+	case PALETTE_BASIC:
 		return (iters == max_iters) ? pixel(0, 0, 0, 255)
 					    : pixel(255, 255, 255, 255);
 
-	case PALETTE_GRAYSCALE:
+	case PALETTE_MONOCHROME:
 		return (iters == max_iters) ? pixel(0, 0, 0, 255)
 					    : pixel(f * 255, f * 255, f * 255, 255);
 
+	case PALETTE_GRAYSCALE:
+		return (iters == max_iters) ? pixel(0, 0, 0, 255) : pixel(v, v, v, 255);
+
 	case PALETTE_HISTOGRAM: {
 		// TODO: actually implement histogram colouring
-
 		return (iters == max_iters) ? pixel(0, 0, 0, 255)
 					    : pixel(f * 255, f * 255, f * 255, 255);
 	} break;
 
 	case PALETTE_SMOOTH: {
-		float smooth_iters = (iters + 1) - (logf(logf(sqrtf(abs2))) / M_LN2);
-		float sf = CLAMP(smooth_iters / max_iters, 0.0f, 1.0f);
-		float v = 255 * (1 - sf);
-
-		return (iters == max_iters) ? pixel(0, 0, 0, 255) : pixel(v, v, v, 255);
+		float hue = 0.95 + 20 * smooth_iters;
+		return (iters == max_iters) ? pixel(0, 0, 0, 255)
+					    : hsv_to_rgb(hue, 0.8, 1.0);
 	} break;
 	}
 }
diff --git a/src/mandelbrot.h b/src/mandelbrot.h
@@ -18,6 +18,7 @@
  */
 
 enum palette_type {
+	PALETTE_BASIC,
 	PALETTE_MONOCHROME,
 	PALETTE_GRAYSCALE,
 	PALETTE_HISTOGRAM,