feat: add vaapi path for video wallpapers on generic gpus

Plugins/ZShell/Wallpaper/shaders/wallpaper_trans_hexagonalize.frag

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+// Hexagonalize crossfade, from gl-transitions.com
+// Author: Fernando Kuteken (MIT)
+// Description: both images turn into hexagons, crossfade, then sharpen again.
+// Hexagonal math from http://www.redblobgames.com/grids/hexagons/
+//
+// Ported to ZShell's GLSL ABI (see wallpaper_trans_bowtie.frag). The
+// gl-transitions `ratio` contextual value is derived from `size`. Optional
+// params are fixed here: steps = 50, horizontalHexagons = 20.
+
+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 steps = 50;
+const float horizontalHexagons = 20.0;
+float ratio;
+
+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);
+}
+
+struct Hexagon {
+	float q;
+	float r;
+	float s;
+};
+
+Hexagon createHexagon(float q, float r) {
+	Hexagon hex;
+	hex.q = q;
+	hex.r = r;
+	hex.s = -q - r;
+	return hex;
+}
+
+Hexagon roundHexagon(Hexagon hex) {
+	float q = floor(hex.q + 0.5);
+	float r = floor(hex.r + 0.5);
+	float s = floor(hex.s + 0.5);
+
+	float deltaQ = abs(q - hex.q);
+	float deltaR = abs(r - hex.r);
+	float deltaS = abs(s - hex.s);
+
+	if (deltaQ > deltaR && deltaQ > deltaS)
+		q = -r - s;
+	else if (deltaR > deltaS)
+		r = -q - s;
+	else
+		s = -q - r;
+
+	return createHexagon(q, r);
+}
+
+Hexagon hexagonFromPoint(vec2 point, float size) {
+	point.y /= ratio;
+	point = (point - 0.5) / size;
+
+	float q = (sqrt(3.0) / 3.0) * point.x + (-1.0 / 3.0) * point.y;
+	float r = 0.0 * point.x + 2.0 / 3.0 * point.y;
+
+	Hexagon hex = createHexagon(q, r);
+	return roundHexagon(hex);
+}
+
+vec2 pointFromHexagon(Hexagon hex, float size) {
+	float x = (sqrt(3.0) * hex.q + (sqrt(3.0) / 2.0) * hex.r) * size + 0.5;
+	float y = (0.0 * hex.q + (3.0 / 2.0) * hex.r) * size + 0.5;
+	return vec2(x, y * ratio);
+}
+
+vec4 transition(vec2 uv) {
+	float dist = 2.0 * min(progress, 1.0 - progress);
+	dist = steps > 0 ? ceil(dist * float(steps)) / float(steps) : dist;
+
+	float size = (sqrt(3.0) / 3.0) * dist / horizontalHexagons;
+
+	vec2 point = dist > 0.0 ? pointFromHexagon(hexagonFromPoint(uv, size), size)
+							: uv;
+
+	return mix(getFromColor(point), getToColor(point), progress);
+}
+
+void main() {
+	vec2 uv = gl_FragCoord.xy / size;
+	ratio = size.x / size.y;
+	outColor = transition(uv);
+}