diff options
Diffstat (limited to 'gst/gl/effects/gstgleffectssources.c')
| -rw-r--r-- | gst/gl/effects/gstgleffectssources.c | 57 |
1 files changed, 18 insertions, 39 deletions
diff --git a/gst/gl/effects/gstgleffectssources.c b/gst/gl/effects/gstgleffectssources.c index f14c391..1d77f2b 100644 --- a/gst/gl/effects/gstgleffectssources.c +++ b/gst/gl/effects/gstgleffectssources.c @@ -455,48 +455,27 @@ const gchar *rgb_to_curve_fragment_source = const gchar *sin_fragment_source = "#extension GL_ARB_texture_rectangle : enable\n" "uniform sampler2DRect tex;" - "vec3 rgb2hsl (vec3 v)" - "{" -/* TODO: check this algorythm */ - " float MIN, MAX;" - " float r, g, b;" - " float h, l, s;" - " float delta;" - " h = 0.0; l = 0.0; s = 0.0;" - " r = v.r; g = v.g; b = v.b;" - " MIN = min (r, min (g, b));" - " MAX = max (r, max (g, b));" - " delta = MAX - MIN;" - " l = (MAX + MIN) / 2.0;" - " if ((MAX - MIN) < 0.0001) { h = 0.0; s = 0.0; }" - " else {" - " if (l <= 0.5) s = (MAX - MIN) / (MAX + MIN);" - " else s = (MAX - MIN) / (2.0 - MAX - MIN);" - " if (r == MAX) h = (g - b) / delta;" - " else if (g == MAX) h = 2.0 + (b - r) / delta;" - " else h = 4.0 + (r - g) / delta;" - " h *= 60.0;" - " if (h < 0.0) h += 360.0;" - " }" - " return vec3 (h, l, s);" - "}" "void main () {" - " vec3 HSL, RGB;" " vec4 color = texture2DRect (tex, vec2(gl_TexCoord[0].st));" " float luma = dot(color.rgb, vec3(0.2125, 0.7154, 0.0721));" - " HSL = rgb2hsl (color.rgb);" -/* move hls discontinuity away from the desired red zone so we can use - * smoothstep.. to try: convert degrees in radiants, divide by 2 and - * smoothstep cosine */ - " HSL.x += 180.0;" - " if ((HSL.x) > 360.0) HSL.x -= 360.0;" -/* damn, it is extremely hard to get rid of human face reds! */ -/* picked hue is slightly shifted towards violet to prevent this but - * still fails.. maybe hsl is not well suited for this */ - " float a = smoothstep (110.0, 150.0, HSL.x);" - " float b = smoothstep (170.0, 210.0, HSL.x);" - " float alpha = a - b;" - " gl_FragColor = color * alpha + luma * (1.0 - alpha);" +/* calculate hue with the Preucil formula */ + " float cosh = 0.5*(2*color.r - color.g - color.b);" +/* sqrt(3)/2 = 0.866 */ + " float sinh = 0.866*(color.g - color.b);" +/* hue = atan2 h */ + " float tanh = sinh/cosh;" +/* ok this is a little trick I came up because I didn't find any + * detailed proof of the Preucil formula. The issue is that tan(h) is + * pi-periodic so the smoothstep thing gives both reds (h = 0) and + * cyans (h = 180). I don't want to use atan since it requires + * branching and doesn't work on i915. So take only the right half of + * the circle where cosine is positive */ +/* take a slightly purple color trying to get rid of human skin reds */ +/* tanh = +-1.0 for h = +-45, where yellow=60, magenta=-60 */ + " float a = smoothstep (-1.0, -0.5, tanh);" + " float b = smoothstep (-0.1, 0.4, tanh);" + " float mix = (a - b) * step (0.0, cosh);" + " gl_FragColor = color * mix + luma * (1.0 - mix);" "}"; const gchar *interpolate_fragment_source = |