3 files changed, 131 insertions, 1 deletions
diff --git a/src/modules/Makefile.am b/src/modules/Makefile.am
index a291174..2890308 100644
--- a/src/modules/Makefile.am
+++ b/src/modules/Makefile.am
@@ -1 +1 @@
-SUBDIRS = ray roto sparkler stars
+SUBDIRS = plasma ray roto sparkler stars
diff --git a/src/modules/plasma/Makefile.am b/src/modules/plasma/Makefile.am
new file mode 100644
index 0000000..16efeb4
--- /dev/null
+++ b/src/modules/plasma/Makefile.am
@@ -0,0 +1,4 @@
+noinst_LIBRARIES = libplasma.a
+libplasma_a_SOURCES = plasma.c
+libplasma_a_CFLAGS = @ROTOTILLER_CFLAGS@
+libplasma_a_CPPFLAGS = @ROTOTILLER_CFLAGS@ -I@top_srcdir@/src
diff --git a/src/modules/plasma/plasma.c b/src/modules/plasma/plasma.c
new file mode 100644
index 0000000..59c394a
--- /dev/null
+++ b/src/modules/plasma/plasma.c
@@ -0,0 +1,126 @@
+#include <stdint.h>
+#include <inttypes.h>
+#include <math.h>
+
+#include "fb.h"
+#include "rototiller.h"
+
+/* Copyright (C) 2017 Vito Caputo <vcaputo@pengaru.com> */
+
+#define FIXED_TRIG_LUT_SIZE	4096			/* size of the cos/sin look-up tables */
+#define FIXED_BITS		10			/* fractional bits */
+#define FIXED_EXP		(1 << FIXED_BITS)	/* 2^FIXED_BITS */
+#define FIXED_MASK		(FIXED_EXP - 1)		/* fractional part mask */
+#define FIXED_COS(_rad)		costab[(_rad) & (FIXED_TRIG_LUT_SIZE-1)]
+#define FIXED_SIN(_rad)		sintab[(_rad) & (FIXED_TRIG_LUT_SIZE-1)]
+#define FIXED_MULT(_a, _b)	(((_a) * (_b)) >> FIXED_BITS)
+#define FIXED_NEW(_i)		((_i) << FIXED_BITS)
+#define FIXED_TO_INT(_f)	((_f) >> FIXED_BITS)
+
+typedef struct color_t {
+	int	r, g, b;
+} color_t;
+
+
+static inline uint32_t color2pixel(color_t *color)
+{
+	return (FIXED_TO_INT(color->r) << 16) | (FIXED_TO_INT(color->g) << 8) | FIXED_TO_INT(color->b);
+}
+
+
+static void init_plasma(int32_t *costab, int32_t *sintab)
+{
+	int	i;
+
+	/* Generate fixed-point cos & sin LUTs. */
+	for (i = 0; i < FIXED_TRIG_LUT_SIZE; i++) {
+		costab[i] = ((cos((double)2*M_PI*i/FIXED_TRIG_LUT_SIZE))*FIXED_EXP);
+		sintab[i] = ((sin((double)2*M_PI*i/FIXED_TRIG_LUT_SIZE))*FIXED_EXP);
+	}
+}
+
+
+/* Draw a plasma effect */
+static void plasma(fb_fragment_t *fragment)
+{
+	static int32_t	costab[FIXED_TRIG_LUT_SIZE], sintab[FIXED_TRIG_LUT_SIZE];
+	static int	initialized;
+	static unsigned	rr, rr2, rr6, rr8, rr16, rr20, rr12;
+
+	unsigned	stride = fragment->stride / 4, width = fragment->width, height = fragment->height;
+	int		fw2 = FIXED_NEW(width / 2), fh2 = FIXED_NEW(height / 2);
+	int		x, y, cx, cy, dx2, dy2;
+	uint32_t	*buf = fragment->buf;
+	color_t		c = { .r = 0, .g = 0, .b = 0 }, cscale;
+
+	if (!initialized) {
+		initialized = 1;
+
+		init_plasma(costab, sintab);
+	}
+
+	rr2 = rr * 2;
+	rr6 = rr * 6;
+	rr8 = rr * 8;
+	rr16 = rr * 16;
+	rr20 = rr * 20;
+	rr12 = rr * 12;
+
+	/* vary the color channel intensities */
+	cscale.r = FIXED_MULT(FIXED_COS(rr / 2), FIXED_NEW(64)) + FIXED_NEW(64);
+	cscale.g = FIXED_MULT(FIXED_COS(rr / 5), FIXED_NEW(64)) + FIXED_NEW(64);
+	cscale.b = FIXED_MULT(FIXED_COS(rr / 7), FIXED_NEW(64)) + FIXED_NEW(64);
+
+	cx = FIXED_TO_INT(FIXED_MULT(FIXED_COS(rr), fw2) + fw2);
+	cy = FIXED_TO_INT(FIXED_MULT(FIXED_SIN(rr2), fh2) + fh2);
+
+	for (y = 0; y < height; y++) {
+		int	y2 = y << 1;
+		int	y4 = y << 2;
+
+		dy2 = cy - y;
+		dy2 *= dy2;
+
+		for (x = 0; x < width; x++, buf++) {
+			int	v;
+			int	hyp;
+
+			dx2 = cx - x;
+			dx2 *= dx2;
+
+			hyp = (dx2 + dy2) >> 10;	/* XXX: technically this should be a sqrt(), but >> 10 is a whole lot faster. */
+
+			v = FIXED_MULT(	((FIXED_COS(rr8 + hyp * 5)) +
+					(FIXED_SIN(-rr16 + (x << 2))) +
+					(FIXED_COS(rr20 + y4))),
+					FIXED_EXP / 3);	/* XXX: note these '/ 3' get optimized out. */
+			c.r = FIXED_MULT(v, cscale.r) + cscale.r;
+
+			v = FIXED_MULT(	((FIXED_COS(rr12 + (hyp << 2))) +
+					(FIXED_COS(rr6 + (x << 1))) +
+					(FIXED_SIN(rr16 + y2))),
+					FIXED_EXP / 3);
+			c.g = FIXED_MULT(v, cscale.g) + cscale.g;
+
+			v = FIXED_MULT(	((FIXED_SIN(rr6 + hyp * 6)) +
+					(FIXED_COS(-rr12 + x * 5)) +
+					(FIXED_SIN(-rr6 + y2))),
+					FIXED_EXP / 3);
+			c.b = FIXED_MULT(v, cscale.b) + cscale.b;
+
+			*buf = color2pixel(&c);
+		}
+
+		buf += stride;
+	}
+
+	rr += 3;
+}
+
+rototiller_renderer_t	plasma_renderer = {
+	.render = plasma,
+	.name = "plasma",
+	.description = "Oldskool plasma effect",
+	.author = "Vito Caputo <vcaputo@pengaru.com>",
+	.license = "GPLv2",
+};