/* * st-scroll-view-fade.glsl: Edge fade effect for StScrollView * * Copyright 2010 Intel Corporation. * Copyright 2011 Adel Gadllah * * This program is free software; you can redistribute it and/or modify it * under the terms and conditions of the GNU Lesser General Public License, * version 2.1, as published by the Free Software Foundation. * * This program is distributed in the hope it will be useful, but WITHOUT ANY * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for * more details. * * You should have received a copy of the GNU Lesser General Public License * along with this program. If not, see . */ uniform sampler2D tex; uniform float height; uniform float width; uniform float vfade_offset; uniform float hfade_offset; uniform float vvalue; uniform float hvalue; /* * Used to pass the fade area to the shader * * [0][0] = x1 * [0][1] = y1 * [1][0] = x2 * [1][1] = y2 * */ uniform mat2 fade_area; /* * Scale from [0.0, 1.0] to [1.0, 1.0]. Do this by * changing it to scaling [1.0, 0.0] to [0.0, 0.0] * and then transforming the end result. */ #define FADE(gradient, factor) (1.0 - (1.0 - gradient) * factor) void main () { cogl_color_out = cogl_color_in * texture2D (tex, vec2 (cogl_tex_coord_in[0].xy)); float y = height * cogl_tex_coord_in[0].y; float x = width * cogl_tex_coord_in[0].x; if (x < fade_area[0][0] || x > fade_area[1][0] || y < fade_area[0][1] || y > fade_area[1][1]) return; float ratio = 1.0; float fade_bottom_start = fade_area[1][1] - vfade_offset; float fade_right_start = fade_area[1][0] - hfade_offset; bool fade_top = y < vfade_offset && vvalue > 0.0; bool fade_bottom = y > fade_bottom_start && vvalue < 1.0; bool fade_left = x < hfade_offset && hvalue > 0.0; bool fade_right = x > fade_right_start && hvalue < 1.0; float vfade_scale = height / vfade_offset; if (fade_top) { ratio *= FADE((y / vfade_offset), min(vvalue * vfade_scale, 1.0)); } if (fade_bottom) { ratio *= FADE((fade_area[1][1] - y)/(fade_area[1][1] - fade_bottom_start), min((1.0 - vvalue) * vfade_scale, 1.0)); } float hfade_scale = width / hfade_offset; if (fade_left) { ratio *= FADE(x / hfade_offset, min(hvalue * hfade_scale, 1.0)); } if (fade_right) { ratio *= FADE((fade_area[1][0] - x)/(fade_area[1][0] - fade_right_start), min((1.0 - hvalue) * hfade_scale, 1.0)); } cogl_color_out *= ratio; }