X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=padding_effect.frag;h=2dc2d30ffc40efcdf297c9c3016c8c9d9eb2fcd3;hp=4f1adc1fd257f54318f38a7ada6c3e296d29089f;hb=3b9957afac0555a126d1941d7027fb52e29b309a;hpb=207384d5c7b8ce40e57decb0160c91da70d54ee6

diff --git a/padding_effect.frag b/padding_effect.frag
index 4f1adc1..2dc2d30 100644
--- a/padding_effect.frag
+++ b/padding_effect.frag
@@ -1,16 +1,25 @@
-uniform vec2 PREFIX(offset);
-uniform vec2 PREFIX(scale);
-uniform vec2 PREFIX(texcoord_min);
-uniform vec2 PREFIX(texcoord_max);
+// Implicit uniforms:
+// uniform vec2 PREFIX(offset);
+// uniform vec2 PREFIX(scale);
+//
+// uniform vec2 PREFIX(normalized_coords_to_texels);
+// uniform vec2 PREFIX(offset_bottomleft);
+// uniform vec2 PREFIX(offset_topright);
 
 vec4 FUNCNAME(vec2 tc) {
 	tc -= PREFIX(offset);
 	tc *= PREFIX(scale);
 
-	if (any(lessThan(tc, PREFIX(texcoord_min))) ||
-	    any(greaterThan(tc, PREFIX(texcoord_max)))) {
+	vec2 tc_texels = tc * PREFIX(normalized_coords_to_texels);
+	vec2 coverage_bottomleft = clamp(tc_texels + PREFIX(offset_bottomleft), 0.0f, 1.0f);
+	vec2 coverage_topright = clamp(PREFIX(offset_topright) - tc_texels, 0.0f, 1.0f);
+	vec2 coverage_both = coverage_bottomleft * coverage_topright;
+	float coverage = coverage_both.x * coverage_both.y;
+
+	if (coverage <= 0.0f) {
+		// Short-circuit in case the underlying function is expensive to call.
 		return PREFIX(border_color);
+	} else {
+		return mix(PREFIX(border_color), INPUT(tc), coverage);
 	}
-
-	return INPUT(tc);
 }