modules/flow: add colors

This is a first stab at colorizing the output.

The flow field now has two v3f_t datums per cell, direction and
color.

It's a bit pastel-y and color choice/palettes definitely needs
work, at least some gamma correction would make sense.

But I kind of like the pastel look actually, some of the
combinations start looking very 80s aesthetic.

A good way to watch flow's possibilities is:

--module=rtv,channels=flow,duration=10,context_duration=10,caption_duration=0 \
--video=sdl,fullscreen=on --defaults --go

The long-ish duration really gives a chance to get into the
groove of things before switching

3 files changed, 34 insertions, 22 deletions

diff --git a/src/modules/flow/ff.c b/src/modules/flow/ff.c
index a0ab56c..f4280b9 100644
--- a/src/modules/flow/ff.c
+++ b/src/modules/flow/ff.c
@@ -7,8 +7,8 @@
 
 typedef struct ff_t {
 	unsigned	size;
-	v3f_t		*fields[2];
-	void		(*populator)(void *context, unsigned size, const v3f_t *other, v3f_t *field);
+	ff_data_t	*fields[2];
+	void		(*populator)(void *context, unsigned size, const ff_data_t *other, ff_data_t *field);
 	void		*populator_context;
 } ff_t;
 
@@ -39,7 +39,7 @@ ff_t * ff_free(ff_t *ff)
 }
 
 
-ff_t * ff_new(unsigned size, void (*populator)(void *context, unsigned size, const v3f_t *other, v3f_t *field), void *context)
+ff_t * ff_new(unsigned size, void (*populator)(void *context, unsigned size, const ff_data_t *other, ff_data_t *field), void *context)
 {
 	ff_t		*ff;
 
@@ -48,7 +48,7 @@ ff_t * ff_new(unsigned size, void (*populator)(void *context, unsigned size, con
 		return NULL;
 
 	for (int i = 0; i < 2; i++) {
-		ff->fields[i] = calloc(size * size * size, sizeof(v3f_t));
+		ff->fields[i] = calloc(size * size * size, sizeof(ff_data_t));
 		if (!ff->fields[i])
 			return ff_free(ff);
 	}
@@ -64,10 +64,11 @@ ff_t * ff_new(unsigned size, void (*populator)(void *context, unsigned size, con
 }
 
 
-static inline v3f_t ff_sample(v3f_t *field, size_t size, v3f_t *min, v3f_t *max, v3f_t *t)
+static inline ff_data_t ff_sample(ff_data_t *field, size_t size, v3f_t *min, v3f_t *max, v3f_t *t)
 {
-	v3f_t	*a, *b, *c, *d, *e, *f, *g, *h;
-	size_t	ss = size * size;
+	ff_data_t	*a, *b, *c, *d, *e, *f, *g, *h;
+	size_t		ss = size * size;
+	ff_data_t	res;
 
 	a = &field[(size_t)min->x * ss + (size_t)max->y * size + (size_t)min->z];
 	b = &field[(size_t)max->x * ss + (size_t)max->y * size + (size_t)min->z];
@@ -78,16 +79,20 @@ static inline v3f_t ff_sample(v3f_t *field, size_t size, v3f_t *min, v3f_t *max,
 	g = &field[(size_t)min->x * ss + (size_t)min->y * size + (size_t)max->z];
 	h = &field[(size_t)max->x * ss + (size_t)min->y * size + (size_t)max->z];
 
-	return v3f_trilerp(a, b, c, d, e, f, g, h, t);
+	res.direction = v3f_trilerp(&a->direction, &b->direction, &c->direction, &d->direction, &e->direction, &f->direction, &g->direction, &h->direction, t);
+	res.color = v3f_trilerp(&a->color, &b->color, &c->color, &d->color, &e->color, &f->color, &g->color, &h->color, t);
+
+	return res;
 }
 
 
 /* return an interpolated value from ff for the supplied coordinate */
 /* coordinate must be in the range 0-1,0-1,0-1 */
 /* w must be in the range 0-1 and determines how much of field 0 or 1 contributes to the result */
-v3f_t ff_get(ff_t *ff, v3f_t *coordinate, float w)
+ff_data_t ff_get(ff_t *ff, v3f_t *coordinate, float w)
 {
-	v3f_t		scaled, min, max, t, A, B;
+	v3f_t		scaled, min, max, t;
+	ff_data_t	A, B, res;
 
 	assert(w <= 1.f && w >= 0.f);
 	assert(coordinate->x <= 1.f && coordinate->x >= 0.f);
@@ -119,5 +124,8 @@ v3f_t ff_get(ff_t *ff, v3f_t *coordinate, float w)
 	A = ff_sample(ff->fields[0], ff->size, &min, &max, &t);
 	B = ff_sample(ff->fields[1], ff->size, &min, &max, &t);
 
-	return v3f_nlerp(&A, &B, w);
+	res.direction = v3f_nlerp(&A.direction, &B.direction, w);
+	res.color = v3f_nlerp(&A.color, &B.color, w);
+
+	return res;
 }
diff --git a/src/modules/flow/ff.h b/src/modules/flow/ff.h
index 0324ea0..b148c2e 100644
--- a/src/modules/flow/ff.h
+++ b/src/modules/flow/ff.h
@@ -5,9 +5,14 @@
 
 typedef struct ff_t ff_t;
 
-ff_t * ff_new(unsigned size, void (*populator)(void *context, unsigned size, const v3f_t *other, v3f_t *field), void *context);
+typedef struct ff_data_t {
+	v3f_t	direction;
+	v3f_t	color;
+} ff_data_t;
+
+ff_t * ff_new(unsigned size, void (*populator)(void *context, unsigned size, const ff_data_t *other, ff_data_t *field), void *context);
 ff_t * ff_free(ff_t *ff);
-v3f_t ff_get(ff_t *ff, v3f_t *coordinate, float w);
+ff_data_t ff_get(ff_t *ff, v3f_t *coordinate, float w);
 void ff_populate(ff_t *ff, unsigned idx);
 
 #endif
diff --git a/src/modules/flow/flow.c b/src/modules/flow/flow.c
index 636458f..973fad0 100644
--- a/src/modules/flow/flow.c
+++ b/src/modules/flow/flow.c
@@ -48,7 +48,7 @@ typedef struct flow_setup_t {
 } flow_setup_t;
 
 
-static void populator(void *context, unsigned size, const v3f_t *other, v3f_t *field)
+static void populator(void *context, unsigned size, const ff_data_t *other, ff_data_t *field)
 {
 	flow_context_t	*ctxt = context;
 	unsigned	*seedp = &ctxt->til_module_context.seed;
@@ -58,9 +58,11 @@ static void populator(void *context, unsigned size, const v3f_t *other, v3f_t *f
 		for (y = 0; y < size; y++) {
 			for (z = 0; z < size; z++) {
 				v3f_t	v = v3f_rand(seedp, -1.0f, 1.0f);
+				v3f_t	c = v3f_rand(seedp, 0.f, 1.0f);
 				size_t	idx = x * size * size + y * size + z;
 
-				field[idx] = v3f_lerp(&other[idx], &v, .75f);
+				field[idx].direction = v3f_lerp(&other[idx].direction, &v, .75f);
+				field[idx].color = v3f_lerp(&other[idx].color, &c, .75f);
 			}
 		}
 	}
@@ -150,22 +152,19 @@ static void flow_render_fragment(til_module_context_t *context, til_stream_t *st
 	for (unsigned j = 0; j < ctxt->n_elements; j++) {
 		flow_element_t	*e = &ctxt->elements[j];
 		v3f_t		pos = e->position;
-		v3f_t		v = ff_get(ctxt->ff, &pos, w * .5f + .5f);
+		ff_data_t	d = ff_get(ctxt->ff, &pos, w * .5f + .5f);
 
-		v = v3f_mult_scalar(&v, .001f);
+		d.direction = v3f_mult_scalar(&d.direction, .001f);
 
 		for (unsigned k = 0; k < ctxt->n_iters; k++) {
 			unsigned	x, y;
-			v3f_t		color;
 
-			pos = v3f_add(&pos, &v);
+			pos = v3f_add(&pos, &d.direction);
 #define ZCONST 1.0f
 			x = (pos.x * 2.f - 1.f) / (pos.z + ZCONST) * fragment->width + (fragment->width >> 1);
 			y = (pos.y * 2.f - 1.f) / (pos.z + ZCONST) * fragment->height + (fragment->height >> 1) ;
 
-			color.x = color.y = color.z = e->lifetime;
-
-			if (!til_fb_fragment_put_pixel_checked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x, y, color_to_uint32_rgb(color)) ||
+			if (!til_fb_fragment_put_pixel_checked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x, y, color_to_uint32_rgb(d.color)) ||
 			    pos.x < 0.f || pos.x > 1.f ||
 			    pos.y < 0.f || pos.y > 1.f ||
 			    pos.z < 0.f || pos.z > 1.f)