[thanos] Added particle shrink and fade-out during Thanos dissolution.

Telegram/SourceFiles/ui/effects/thanos_effect_renderer.cpp

@@ -30,6 +30,9 @@ constexpr auto kTimeStepMultiplier = 1.0f;
 constexpr auto kAccelerationStartPhase = 1.0f;
 constexpr auto kAccelerationRampPhase = 2.5f;
 constexpr auto kAccelerationMaxMultiplier = 2.2f;
+constexpr auto kDisappearStartPhase = kMaxPhaseDuration * 0.15f;
+constexpr auto kDisappearDuration
+	= kMaxPhaseDuration - kDisappearStartPhase;
 constexpr auto kMaxParticleCount = uint32_t(120000);
 
 const float kQuadVertices[kQuadVertexCount * 2] = {
@@ -61,6 +64,7 @@ struct alignas(16) RenderUniforms {
 	float rect[4];
 	float size[2];
 	uint32_t particleResolution[2];
+	float scale[4];
 };
 static_assert(sizeof(RenderUniforms) % 16 == 0);
 
@@ -77,6 +81,15 @@ static_assert(sizeof(RenderUniforms) % 16 == 0);
 		+ ((kAccelerationMaxMultiplier - 1.0f) * smooth);
 }
 
+[[nodiscard]] float DisappearProgress(float phase) {
+	const auto t = std::clamp(
+		(phase - kDisappearStartPhase) / kDisappearDuration,
+		0.0f,
+		1.0f);
+	const auto oneMinus = 1.0f - t;
+	return 1.0f - (oneMinus * oneMinus * oneMinus);
+}
+
 [[nodiscard]] QShader LoadShader(const QString &name) {
 	return Rhi::ShaderFromFile(u":/shaders/"_q + name + u".qsb"_q);
 }
@@ -358,6 +371,12 @@ void ThanosEffectRenderer::render(
 			uni.size[1] = float(item.rect.height());
 			uni.particleResolution[0] = item.particleCountX;
 			uni.particleResolution[1] = item.particleCountY;
+			const auto disappearProgress = DisappearProgress(item.phase);
+			const auto inverseDisappear = 1.0f - disappearProgress;
+			uni.scale[0] = inverseDisappear;
+			uni.scale[1] = 0.0f;
+			uni.scale[2] = inverseDisappear;
+			uni.scale[3] = 0.0f;
 
 			renderRub->updateDynamicBuffer(
 				item.renderUniformBuffer,

Telegram/shaders/thanos.vert

@@ -12,6 +12,7 @@ layout(std140, binding = 0) uniform Params {
 	vec4 rect;
 	vec2 size;
 	uvec2 particleResolution;
+	vec4 scale;
 };
 
 void main() {
@@ -25,7 +26,10 @@ void main() {
 	v_texcoord = (topLeft + inQuadPos * particleSize) / size;
 
 	topLeft += inOffset;
-	vec2 position = topLeft + inQuadPos * particleSize;
+	float scaleFactor = scale.x;
+	vec2 center = topLeft + (particleSize * 0.5);
+	vec2 position
+		= center + ((inQuadPos - vec2(0.5)) * particleSize * scaleFactor);
 
 	vec2 ndc;
 	ndc.x = rect.x + position.x / size.x * rect.z;
@@ -35,5 +39,5 @@ void main() {
 
 	gl_Position = vec4(ndc, 0.0, 1.0);
 
-	v_alpha = clamp(inLifetime / 0.6, 0.0, 1.0);
+	v_alpha = clamp(inLifetime / 0.6, 0.0, 1.0) * scale.z;
 }