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author | Tavian Barnes <tavianator@gmail.com> | 2011-05-20 18:59:18 -0600 |
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committer | Tavian Barnes <tavianator@gmail.com> | 2011-05-20 18:59:18 -0600 |
commit | 18b89c6edc29a009b1419e6d34bc3eef2dd911b9 (patch) | |
tree | 02f36651220fbd0821c94d6c13848bd9beb59098 /libdimension/color.c | |
parent | 250b980002419746fc099c7633b9600a15afb1c6 (diff) | |
download | dimension-18b89c6edc29a009b1419e6d34bc3eef2dd911b9.tar.xz |
Switch to Blender model of filtered transparency.
Diffstat (limited to 'libdimension/color.c')
-rw-r--r-- | libdimension/color.c | 67 |
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; } |