Resistance: Retribution: Add smoke trail nodes at most every 1/30s

The debris smoke trails add a node on every update, so at 60fps the smoke was twice as dense
as at 30fps and spawned twice as many trails. Keep the nodes 1/30 of the effect's clock apart
instead. In the angel boss explosion the display list now peaks at 0x483ec bytes without the
overflow guard's help, against 0x637f4 before.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Core/HLE/ReplaceTables.cpp

@@ -1488,6 +1488,7 @@ static int Hook_resistance_draw_trail() {
 	// time, so the higher the frame rate, the more of them are alive. After the angel boss in Bonn the
 	// trails behind the debris make the display list overflow its buffer at 60fps, into the music
 	// stream and beyond (#19755). Locking the CPU to 222MHz, which slows the frame rate, avoids it.
+	// resistance_update_trail now limits the node rate, so this is a backstop.
 	// The game keeps its two list buffers and their limits next to the write pointer, but doesn't
 	// check them here. Hooked where the node count is about to become the loop count: when the
 	// current buffer is nearly full, skip the trail by making the count zero.
@@ -1511,6 +1512,37 @@ static int Hook_resistance_draw_trail() {
 	return 0;
 }
 
+static int Hook_resistance_update_trail() {
+	// The trail adds a node on every update that its emitter's rate allows (one per update at most,
+	// and the explosion debris always allow one), and the effect's clock advances 1/60 per update
+	// at 60fps. Keep the nodes at least 1/30 of that clock apart, as if the game ran at 30fps, so
+	// running faster doesn't pack the smoke denser and multiply the trails (#19755). Hooked where the
+	// accumulator is about to be tested: holding it under the threshold postpones the node.
+	const u32 trail = currentMIPS->r[MIPS_REG_S0];
+	if (!Memory::IsValid4AlignedRange(trail + 0x140, 0x3C)) {
+		return 0;
+	}
+	const u32 emitter = Memory::ReadUnchecked_U32(trail + 0x140);
+	const u32 nodes = Memory::ReadUnchecked_U32(trail + 0x144);
+	const s32 count = (s32)Memory::ReadUnchecked_U32(trail + 0x178);
+	if (count <= 0 || !Memory::IsValid4AlignedAddress(emitter + 8) || !Memory::IsValid4AlignedAddress(nodes + (count - 1) * 4)) {
+		return 0;
+	}
+	const u32 lastNode = Memory::ReadUnchecked_U32(nodes + (count - 1) * 4);
+	if (!Memory::IsValid4AlignedAddress(lastNode + 0x50)) {
+		return 0;
+	}
+	const float now = currentMIPS->f[20];
+	const float lastNodeTime = Memory::ReadUnchecked_Float(lastNode + 0x50);
+	// Updates come 1/60 apart, so this lets every other one through.
+	if (now - lastNodeTime < 1.0f / 30.0f - 0.001f) {
+		const float rate = Memory::ReadUnchecked_Float(emitter + 8);
+		const float acc = Memory::ReadUnchecked_Float(trail + 0x170);
+		Memory::WriteUnchecked_Float(std::min(acc, 1.0f - rate - 0.001f), trail + 0x170);
+	}
+	return 0;
+}
+
 static int Hook_katamari_render_check() {
 	if (!Memory::IsValidRange(currentMIPS->r[MIPS_REG_A0] + 0x3C, 8)) {
 		return 0;
@@ -1851,6 +1883,7 @@ static const ReplacementTableEntry entries[] = {
 	{ "everybodysgolf_spinner_background", &Hook_everybodysgolf_spinner_background, 0, REPFLAG_HOOKENTER, 0x138 },
 	{ "codedarms_stencil_check", &Hook_codedarms_stencil_check, 0, REPFLAG_HOOKENTER, 0x8C },
 	{ "resistance_draw_trail", &Hook_resistance_draw_trail, 0, REPFLAG_HOOKENTER, 0x198 },
+	{ "resistance_update_trail", &Hook_resistance_update_trail, 0, REPFLAG_HOOKENTER, 0x438 },
 	{}
 };
 

Core/MIPS/MIPSAnalyst.cpp

@@ -377,6 +377,7 @@ static const HardHashTableEntry hardcodedHashes[] = {
 	{ 0xa85fe8abb88b1c6f, 52, "vector_sub_t", },
 	{ 0xa9194e55cc586557, 268, "memcpy", },
 	{ 0xa91b3d60bd75105b, 28, "vadd_t", },
+	{ 0xaaf1cc9399336a21, 1872, "resistance_update_trail", },
 	{ 0xab97ec58c58a7c75, 52, "sceVfpuVector3Div", },
 	{ 0xac84fa7571895c9a, 68, "memcpy", }, // Marvel Ultimate Alliance 2
 	{ 0xacc2c11c3ea28320, 268, "ceilf", },