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scroll-view-fade: Fade gradients when near edges

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Rather than sharply transitioning to gradients, fade them out when
near the edge of the scroll view.

https://bugzilla.gnome.org/show_bug.cgi?id=689249
This commit is contained in:
Jasper St. Pierre 2012-11-28 18:30:20 -05:00
parent 69347fff09
commit b4f5f1e461
1 changed files with 13 additions and 4 deletions
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17
src/st/st-scroll-view-fade.glsl
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@ -38,6 +38,13 @@ uniform float hvalue;
*/
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 - (1 - gradient) * factor)
void main ()
{
cogl_color_out = cogl_color_in * texture2D (tex, vec2 (cogl_tex_coord_in[0].xy));
@ -57,20 +64,22 @@ void main ()
bool fade_left = x < hfade_offset && hvalue > 0;
bool fade_right = x > fade_right_start && hvalue < 1;
float vfade_scale = height / vfade_offset;
if (fade_top) {
ratio *= (y / vfade_offset);
ratio *= FADE((y / vfade_offset), min(vvalue * vfade_scale, 1.0));
}
if (fade_bottom) {
ratio *= (fade_area[1][1] - y)/(fade_area[1][1] - fade_bottom_start);
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 *= (x / hfade_offset);
ratio *= FADE(x / hfade_offset, min(hvalue * hfade_scale, 1.0));
}
if (fade_right) {
ratio *= (fade_area[1][0] - x)/(fade_area[1][0] - fade_right_start);
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;