[Radiance-general] adding color pattern

[Ian Tester]

On Mon, 26 Sep 2005 19:41:00 -0400
<bei.xiao at gmail.com> wrote:

> hi,
>   I want to generate a pool-ball like object. Basically, instead of
> having a uniform colored object, I want to add some other color to the
> object but the object is made of uniform material. Can I generate a
> .cal file and directly manipulate the color at specific location using
> local coordinates and use colorFunc to add the pattern? It sounds
> trival to do but I m having trouble generating it right. Thank you
> very much.

Sorry for the late reply. Here's some examples from my work:

o_ball-1.rad:
----
void mixfunc ball_1_surf
6	clear_plastic	yellow_billiard
	num_disc	billiards.cal
	-s 57.15
0
1	18.0

ball_1_surf sphere ball_1
0
0
4	0	0	0
	57.15

white_flat colorpict ball_1_unlit
9	unlit_red	unlit_green	unlit_blue
	lcd-01.pic
	billiards.cal	ballmap_u	ballmap_v
	-s 57.15
0
3	0.65		0.45		0.45

void mixpict ball_1_num
9	redled		ball_1_unlit
	lit		lcd-01.pic
	billiards.cal	ballmap_u	ballmap_v
	-s 57.15
0
0

ball_1_num ring face-1a
0
0
8	0	54.35288	0
	0	1		0
	0	17.660321

ball_1_num ring face-1b
0
0
8	0	-54.35288	0
	0	-1		0
	0	17.660321
----


o_ball-9.rad:
----
white_billiard colorfunc ball_9_col
6	bh_red		bh_green	bh_blue
	billiards.cal
	-s 57.15
0
4	0.9		0.9		0.0
	60.0

void mixfunc ball_9_surf
6	clear_plastic	ball_9_col
	num_disc	billiards.cal
	-s 57.15
0
1	18.0

ball_9_surf sphere ball_9
0
0
4	0	0	0
	57.15

white_flat colorpict ball_9_unlit
9	unlit_red	unlit_green	unlit_blue
	lcd-09.pic
	billiards.cal	ballmap_u	ballmap_v
	-s 57.15
0
3	0.65		0.45		0.45

void mixpict ball_9_num
9	redled		ball_9_unlit
	lit		lcd-09.pic
	billiards.cal	ballmap_u	ballmap_v
	-s 57.15
0
0

ball_9_num ring face-9a
0
0
8	0	54.35288	0
	0	1		0
	0	17.660321

ball_9_num ring face-9b
0
0
8	0	-54.35288	0
	0	-1		0
	0	17.660321
----


m_balls.rad:
----
void plastic white_flat
0
0
5	0.6	0.6	0.6
	0.0	0.1

void texfunc rough1
4	gloss_dx	gloss_dy	gloss_dz
	gloss.cal
0
3	0.02	0.02	0.02

void plastic white_billiard
0
0
5	0.6	0.6	0.6
	0.03	0.02

# 0.9	0.9	0.0
void plastic yellow_billiard
0
0
5	0.54	0.54	0.0
	0.03	0.02

etc...

rough1 dielectric clear_plastic
0
0
5	1.25	1.25	1.25
	1.3	0.0

void light redled
0
0
3	500	0	0
----


billiards.cal:
----
ballmap_u = 0.5+if(Py, -Px, Px)*0.5;
ballmap_v = 0.5+Pz*0.5;

RADIAN : 180 / PI;

py_angle = acos(abs(Py)) * RADIAN;
pz_angle = acos(abs(Pz)) * RADIAN;

num_disc = if(A1 - py_angle, 1, 0);

bh_red = if(A4 - pz_angle, 1.0, A1);
bh_green = if(A4 - pz_angle, 1.0, A2);
bh_blue = if(A4 - pz_angle, 1.0, A3);

rgb_grey(r,g,b) = r + g + b;

max3(a,b,c) : if(a-b, if(a-c, a, c), if(b-c, b, c));

lit(r,g,b) = r - (1/255);
unlit(r,g,b) : g - (1/255);
unlit_red(r,g,b) = clip((unlit(r,g,b) * A1) + (1 - unlit(r,g,b)));
unlit_green(r,g,b) = clip((unlit(r,g,b) * A2) + (1 - unlit(r,g,b)));
unlit_blue(r,g,b) = clip((unlit(r,g,b) * A3) + (1 - unlit(r,g,b)));

on : 1;
off : 0;

half : 0.5;
----


Hopefully that'll help you. All of the balls are very similar. Just have
your seven colours defined (in m_balls.rad in my example) plus black for
the 8-ball. Then it's just a copy-and-paste job for the other balls, just
changing the names slightly. The 'low' balls have a solid colour, the
'high' balls have only a band of colour. That's what the
bh_{red,green,blue} functions are modifying. Then just place the balls in
the scene with an !xform line. This is needed to have the functions
modifying the material transform with the rest of the ball.

bye