feat: add vaapi path for video wallpapers on generic gpus

Plugins/ZShell/Wallpaper/shaders/wallpaper_trans_doom_melt.frag

@@ -0,0 +1,72 @@
+// Doom-style melt wipe, from gl-transitions.com
+// Author: Zeh Fernando (MIT)
+// Description: the outgoing image melts down in uneven columns, like the Doom
+// screen wipe. Fully procedural (no displacement texture).
+//
+// Ported to ZShell's GLSL ABI (see wallpaper_trans_bowtie.frag). Optional
+// gl-transitions params are fixed here: bars = 30, amplitude = 2.0,
+// noise = 0.1, frequency = 0.5, dripScale = 0.5.
+
+uniform sampler2D from;
+uniform sampler2D to;
+uniform vec2 size;
+uniform vec4 fromCrop;
+uniform vec4 toCrop;
+uniform float progress;
+uniform float fromFlip;
+uniform float toFlip;
+
+out vec4 outColor;
+
+const int bars = 30;
+const float amplitude = 2.0;
+const float noise = 0.1;
+const float frequency = 0.5;
+const float dripScale = 0.5;
+
+vec4 getFromColor(vec2 uv) {
+	vec2 s = vec2(uv.x, fromFlip > 0.5 ? 1.0 - uv.y : uv.y);
+	return texture(from, fromCrop.xy + s * fromCrop.zw);
+}
+
+vec4 getToColor(vec2 uv) {
+	vec2 s = vec2(uv.x, toFlip > 0.5 ? 1.0 - uv.y : uv.y);
+	return texture(to, toCrop.xy + s * toCrop.zw);
+}
+
+float rand(int num) {
+	return fract(mod(float(num) * 67123.313, 12.0) * sin(float(num) * 10.3) *
+				 cos(float(num)));
+}
+
+float wave(int num) {
+	float fn = float(num) * frequency * 0.1 * float(bars);
+	return cos(fn * 0.5) * cos(fn * 0.13) * sin((fn + 10.0) * 0.3) / 2.0 + 0.5;
+}
+
+float drip(int num) {
+	return sin(float(num) / float(bars - 1) * 3.141592) * dripScale;
+}
+
+float pos(int num) {
+	return (noise == 0.0 ? wave(num)
+						 : mix(wave(num), rand(num), noise)) +
+		   (dripScale == 0.0 ? 0.0 : drip(num));
+}
+
+vec4 transition(vec2 uv) {
+	int bar = int(uv.x * float(bars));
+	float scale = 1.0 + pos(bar) * amplitude;
+	float phase = progress * scale;
+	float posY = uv.y;
+
+	if (phase + posY < 1.0) {
+		return getFromColor(vec2(uv.x, uv.y + phase));
+	}
+	return getToColor(uv);
+}
+
+void main() {
+	vec2 uv = gl_FragCoord.xy / size;
+	outColor = transition(uv);
+}