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authorTavian Barnes <tavianator@gmail.com>2011-05-20 18:59:18 -0600
committerTavian Barnes <tavianator@gmail.com>2011-05-20 18:59:18 -0600
commit18b89c6edc29a009b1419e6d34bc3eef2dd911b9 (patch)
tree02f36651220fbd0821c94d6c13848bd9beb59098 /libdimension/color.c
parent250b980002419746fc099c7633b9600a15afb1c6 (diff)
downloaddimension-18b89c6edc29a009b1419e6d34bc3eef2dd911b9.tar.xz
Switch to Blender model of filtered transparency.
Diffstat (limited to 'libdimension/color.c')
-rw-r--r--libdimension/color.c67
1 files changed, 44 insertions, 23 deletions
diff --git a/libdimension/color.c b/libdimension/color.c
index 24a4574..07d8ed8 100644
--- a/libdimension/color.c
+++ b/libdimension/color.c
@@ -30,71 +30,71 @@ const dmnsn_color dmnsn_black = {
.R = 0.0,
.G = 0.0,
.B = 0.0,
+ .trans = 0.0,
.filter = 0.0,
- .trans = 0.0
};
const dmnsn_color dmnsn_white = {
.R = 1.0,
.G = 1.0,
.B = 1.0,
+ .trans = 0.0,
.filter = 0.0,
- .trans = 0.0
};
const dmnsn_color dmnsn_clear = {
.R = 0.0,
.G = 0.0,
.B = 0.0,
+ .trans = 1.0,
.filter = 0.0,
- .trans = 1.0
};
const dmnsn_color dmnsn_red = {
.R = 1.0,
.G = 0.0,
.B = 0.0,
+ .trans = 0.0,
.filter = 0.0,
- .trans = 0.0
};
const dmnsn_color dmnsn_green = {
.R = 0.0,
.G = 1.0,
.B = 0.0,
+ .trans = 0.0,
.filter = 0.0,
- .trans = 0.0
};
const dmnsn_color dmnsn_blue = {
.R = 0.0,
.G = 0.0,
.B = 1.0,
+ .trans = 0.0,
.filter = 0.0,
- .trans = 0.0
};
const dmnsn_color dmnsn_magenta = {
.R = 1.0,
.G = 0.0,
.B = 1.0,
+ .trans = 0.0,
.filter = 0.0,
- .trans = 0.0
};
const dmnsn_color dmnsn_orange = {
.R = 1.0,
.G = 0.5,
.B = 0.0,
+ .trans = 0.0,
.filter = 0.0,
- .trans = 0.0
};
const dmnsn_color dmnsn_yellow = {
.R = 1.0,
.G = 1.0,
.B = 0.0,
+ .trans = 0.0,
.filter = 0.0,
- .trans = 0.0
};
const dmnsn_color dmnsn_cyan = {
.R = 0.0,
.G = 1.0,
.B = 1.0,
.filter = 0.0,
- .trans = 0.0
+ .trans = 0.0,
};
/* Greyscale color intensity */
@@ -111,11 +111,19 @@ dmnsn_color_add(dmnsn_color c1, dmnsn_color c2)
{
dmnsn_color ret = dmnsn_new_color(c1.R + c2.R, c1.G + c2.G, c1.B + c2.B);
+ /* Switch back into absolute filter and transmittance space */
double n1 = dmnsn_color_intensity(c1), n2 = dmnsn_color_intensity(c2);
- if (n1 + n2 != 0.0) {
- ret.filter = (n1*c1.filter + n2*c2.filter)/(n1 + n2);
- }
- ret.trans = c1.trans + c2.trans;
+ double f1 = c1.filter*c1.trans, f2 = c2.filter*c2.trans;
+ double t1 = c1.trans - f1, t2 = c2.trans - f2;
+ double f = 0.0;
+ if (n1 + n2 >= dmnsn_epsilon)
+ f = (n1*f1 + n2*f2)/(n1 + n2);
+ double t = t1 + t2;
+
+ /* Switch back */
+ ret.trans = f + t;
+ if (ret.trans >= dmnsn_epsilon)
+ ret.filter = f/ret.trans;
return ret;
}
@@ -138,8 +146,8 @@ dmnsn_color_gradient(dmnsn_color c1, dmnsn_color c2, double n)
n*(c2.R - c1.R) + c1.R,
n*(c2.G - c1.G) + c1.G,
n*(c2.B - c1.B) + c1.B,
- n*(c2.filter - c1.filter) + c1.filter,
- n*(c2.trans - c1.trans) + c1.trans
+ n*(c2.trans - c1.trans) + c1.trans,
+ n*(c2.filter - c1.filter) + c1.filter
);
}
@@ -147,15 +155,28 @@ dmnsn_color_gradient(dmnsn_color c1, dmnsn_color c2, double n)
dmnsn_color
dmnsn_filter_light(dmnsn_color light, dmnsn_color filter)
{
- dmnsn_color transmitted = dmnsn_color_mul(filter.trans, light);
+ dmnsn_color transmitted = dmnsn_color_mul(
+ (1.0 - filter.filter)*filter.trans,
+ light
+ );
dmnsn_color filtered = dmnsn_color_mul(
- filter.filter,
+ filter.filter*filter.trans,
dmnsn_color_illuminate(filter, light)
);
dmnsn_color ret = dmnsn_color_add(transmitted, filtered);
- ret.filter = light.filter*dmnsn_color_intensity(filtered)
- + filter.filter*light.trans + filter.trans*light.filter;
- ret.trans = filter.trans*light.trans;
+
+ /* Switch back into absolute filter and transmittance space */
+ double lf = light.filter*light.trans, ff = filter.filter*filter.trans;
+ double lt = light.trans - lf, ft = filter.trans - ff;
+ double f = lf*(dmnsn_color_intensity(filtered) + ft) + lt*ff;
+ double t = ft*lt;
+
+ /* Switch back */
+ ret.trans = f + t;
+ ret.filter = 0.0;
+ if (ret.trans >= dmnsn_epsilon)
+ ret.filter = f/ret.trans;
+
return ret;
}
@@ -164,11 +185,11 @@ dmnsn_color
dmnsn_apply_translucency(dmnsn_color filtered, dmnsn_color filter)
{
dmnsn_color ret = dmnsn_color_add(
- dmnsn_color_mul(1.0 - (filter.filter + filter.trans), filter),
+ dmnsn_color_mul(1.0 - filter.trans, filter),
filtered
);
- ret.filter = filtered.filter;
ret.trans = filtered.trans;
+ ret.filter = filtered.filter;
return ret;
}