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

1 files changed, 7 insertions, 2 deletions

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