gtk/gsk/gl/resources/outset_shadow.glsl
Matthias Clasen ad65db901a gsk: Normalize rects in GLSL
Our coverage computation only works for well-behaved
rects and rounded rects. But our modelview transform
might flip x or y around, causing things to fail.

Add functions to normalize rects and rounded rects,
and use it whenever we transform a rounded rect in GLSL.
2023-05-01 13:43:33 -04:00

36 lines
912 B
GLSL

// VERTEX_SHADER:
// outset_shadow.glsl
uniform vec4[3] u_outline_rect;
_OUT_ vec4 final_color;
_OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outline;
void main() {
gl_Position = u_projection * u_modelview * vec4(aPosition, 0.0, 1.0);
vUv = vec2(aUv.x, aUv.y);
final_color = gsk_scaled_premultiply(aColor, u_alpha);
GskRoundedRect outline = gsk_create_rect(u_outline_rect);
gsk_rounded_rect_transform(outline, u_modelview);
gsk_rounded_rect_normalize(outline);
gsk_rounded_rect_encode(outline, transformed_outline);
}
// FRAGMENT_SHADER:
// outset_shadow.glsl
_IN_ vec4 final_color;
_IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outline;
void main() {
vec2 frag = gsk_get_frag_coord();
float alpha = GskTexture(u_source, vUv).a;
alpha *= (1.0 - clamp(gsk_rounded_rect_coverage(gsk_decode_rect(transformed_outline), frag), 0.0, 1.0));
gskSetScaledOutputColor(final_color, alpha);
}