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1 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
2 /*
3 * Copyright (C) 2010-2012 Inclusive Design Research Centre, OCAD University.
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library. If not, see <http://www.gnu.org/licenses/>.
17 *
18 * Author:
19 * Joseph Scheuhammer <clown@alum.mit.edu>
20 */
21
22 /**
23 * SECTION:shell-invert-lightness-effect
24 * @short_description: A colorization effect where lightness is inverted but
25 * color is not.
26 * @see_also: #ClutterEffect, #ClutterOffscreenEffect
27 *
28 * #ShellInvertLightnessEffect is a sub-class of #ClutterEffect that enhances
29 * the appearance of a clutter actor. Specifically it inverts the lightness
30 * of a #ClutterActor (e.g., darker colors become lighter, white becomes black,
31 * and white, black).
32 */
33
34 #define SHELL_INVERT_LIGHTNESS_EFFECT_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST ((klass), SHELL_TYPE_INVERT_LIGHTNESS_EFFECT, ShellInvertLightnessEffectClass))
35 #define SHELL_IS_INVERT_EFFECT_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), SHELL_TYPE_INVERT_LIGHTNESS_EFFECT))
36 #define SHELL_INVERT_LIGHTNESS_EFFECT_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS ((obj), SHELL_TYPE_INVERT_LIGHTNESS_EFFEC, ShellInvertLightnessEffectClass))
37
38 #define CLUTTER_ENABLE_EXPERIMENTAL_API
39
40 #include "shell-invert-lightness-effect.h"
41
42 #include <cogl/cogl.h>
43
44 struct _ShellInvertLightnessEffect
45 {
46 ClutterOffscreenEffect parent_instance;
47
48 gint tex_width;
49 gint tex_height;
50
51 CoglPipeline *pipeline;
52 };
53
54 struct _ShellInvertLightnessEffectClass
55 {
56 ClutterOffscreenEffectClass parent_class;
57
58 CoglPipeline *base_pipeline;
59 };
60
61 /* Lightness inversion in GLSL.
62 */
63 static const gchar *invert_lightness_source =
64 "cogl_texel = texture2D (cogl_sampler, cogl_tex_coord.st);\n"
65 "vec3 effect = vec3 (cogl_texel);\n"
66 "\n"
67 "float maxColor = max (cogl_texel.r, max (cogl_texel.g, cogl_texel.b));\n"
68 "float minColor = min (cogl_texel.r, min (cogl_texel.g, cogl_texel.b));\n"
69 "float lightness = (maxColor + minColor) / 2.0;\n"
70 "\n"
71 "float delta = (1.0 - lightness) - lightness;\n"
72 "effect.rgb = (effect.rgb + delta);\n"
73 "\n"
74 "cogl_texel = vec4 (effect, cogl_texel.a);\n";
75
76 G_DEFINE_TYPE (ShellInvertLightnessEffect,
77 shell_invert_lightness_effect,
78 CLUTTER_TYPE_OFFSCREEN_EFFECT);
79
80 static gboolean
81 shell_invert_lightness_effect_pre_paint (ClutterEffect *effect)
82 {
83 ShellInvertLightnessEffect *self = SHELL_INVERT_LIGHTNESS_EFFECT (effect);
84 ClutterEffectClass *parent_class;
85
86 if (!clutter_actor_meta_get_enabled (CLUTTER_ACTOR_META (effect)))
87 return FALSE;
88
89 if (!clutter_feature_available (CLUTTER_FEATURE_SHADERS_GLSL))
90 {
91 /* if we don't have support for GLSL shaders then we
92 * forcibly disable the ActorMeta
93 */
94 g_warning ("Unable to use the ShellInvertLightnessEffect: the "
95 "graphics hardware or the current GL driver does not "
96 "implement support for the GLSL shading language.");
97 clutter_actor_meta_set_enabled (CLUTTER_ACTOR_META (self), FALSE);
98 return FALSE;
99 }
100
101 parent_class =
102 CLUTTER_EFFECT_CLASS (shell_invert_lightness_effect_parent_class);
103 if (parent_class->pre_paint (effect))
104 {
105 ClutterOffscreenEffect *offscreen_effect =
106 CLUTTER_OFFSCREEN_EFFECT (effect);
107 CoglHandle texture;
108
109 texture = clutter_offscreen_effect_get_texture (offscreen_effect);
110 self->tex_width = cogl_texture_get_width (texture);
111 self->tex_height = cogl_texture_get_height (texture);
112
113 cogl_pipeline_set_layer_texture (self->pipeline, 0, texture);
114
115 return TRUE;
116 }
117 else
118 return FALSE;
119 }
120
121 static void
122 shell_invert_lightness_effect_paint_target (ClutterOffscreenEffect *effect)
123 {
124 ShellInvertLightnessEffect *self = SHELL_INVERT_LIGHTNESS_EFFECT (effect);
125 ClutterActor *actor;
126 guint8 paint_opacity;
127
128 actor = clutter_actor_meta_get_actor (CLUTTER_ACTOR_META (effect));
129 paint_opacity = clutter_actor_get_paint_opacity (actor);
130
131 cogl_pipeline_set_color4ub (self->pipeline,
132 paint_opacity,
133 paint_opacity,
134 paint_opacity,
135 paint_opacity);
136 cogl_push_source (self->pipeline);
137
138 cogl_rectangle (0, 0, self->tex_width, self->tex_height);
139
140 cogl_pop_source ();
141 }
142
143 static void
144 shell_invert_lightness_effect_dispose (GObject *gobject)
145 {
146 ShellInvertLightnessEffect *self = SHELL_INVERT_LIGHTNESS_EFFECT (gobject);
147
148 if (self->pipeline != NULL)
149 {
150 cogl_object_unref (self->pipeline);
151 self->pipeline = NULL;
152 }
153
154 G_OBJECT_CLASS (shell_invert_lightness_effect_parent_class)->dispose (gobject);
155 }
156
157 static void
158 shell_invert_lightness_effect_class_init (ShellInvertLightnessEffectClass *klass)
159 {
160 ClutterEffectClass *effect_class = CLUTTER_EFFECT_CLASS (klass);
161 GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
162 ClutterOffscreenEffectClass *offscreen_class;
163
164 offscreen_class = CLUTTER_OFFSCREEN_EFFECT_CLASS (klass);
165 offscreen_class->paint_target = shell_invert_lightness_effect_paint_target;
166
167 effect_class->pre_paint = shell_invert_lightness_effect_pre_paint;
168
169 gobject_class->dispose = shell_invert_lightness_effect_dispose;
170 }
171
172 static void
173 shell_invert_lightness_effect_init (ShellInvertLightnessEffect *self)
174 {
175 ShellInvertLightnessEffectClass *klass;
176 klass = SHELL_INVERT_LIGHTNESS_EFFECT_GET_CLASS (self);
177
178 if (G_UNLIKELY (klass->base_pipeline == NULL))
179 {
180 CoglSnippet *snippet;
181 CoglContext *ctx =
182 clutter_backend_get_cogl_context (clutter_get_default_backend ());
183
184 klass->base_pipeline = cogl_pipeline_new (ctx);
185
186 snippet = cogl_snippet_new (COGL_SNIPPET_HOOK_TEXTURE_LOOKUP,
187 NULL,
188 NULL);
189 cogl_snippet_set_replace (snippet, invert_lightness_source);
190 cogl_pipeline_add_layer_snippet (klass->base_pipeline, 0, snippet);
191 cogl_object_unref (snippet);
192
193 cogl_pipeline_set_layer_null_texture (klass->base_pipeline,
194 0, /* layer number */
195 COGL_TEXTURE_TYPE_2D);
196 }
197
198 self->pipeline = cogl_pipeline_copy (klass->base_pipeline);
199 }
200
201 /**
202 * shell_invert_lightness_effect_new:
203 *
204 * Creates a new #ShellInvertLightnessEffect to be used with
205 * clutter_actor_add_effect()
206 *
207 * Return value: (transfer full): the newly created
208 * #ShellInvertLightnessEffect or %NULL. Use g_object_unref() when done.
209 */
210 ClutterEffect *
211 shell_invert_lightness_effect_new (void)
212 {
213 return g_object_new (SHELL_TYPE_INVERT_LIGHTNESS_EFFECT, NULL);
214 }