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use a more reasonable linked list approach for direct trigger collisions
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@douira
douira committed Nov 6, 2023
1 parent 166522b commit ac3d1de
Showing 1 changed file with 46 additions and 65 deletions.
111 changes: 46 additions & 65 deletions src/main/java/me/jellysquid/mods/sodium/client/render/chunk/gfni/DirectTriggers.java
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@ private class DirectTriggerData {
final ChunkSectionPos sectionPos;
private Vector3dc sectionCenter;
final DynamicData dynamicData;
DirectTriggerData next;

/**
* Absolute camera position at the time of the last trigger.
Expand Down Expand Up @@ -108,45 +109,19 @@ private static double angleCos(double ax, double ay, double az, double bx, doubl
private void insertDirectAngleTrigger(DirectTriggerData data, Vector3dc cameraPos, double remainingAngle) {
double triggerCameraSectionCenterDist = data.getSectionCenterTriggerCameraDist();
double centerMinDistance = Math.tan(remainingAngle) * (triggerCameraSectionCenterDist - SECTION_CENTER_DIST);
this.insertJitteredTrigger(this.accumulatedDistance + centerMinDistance, data);
this.insertTrigger(this.accumulatedDistance + centerMinDistance, data);
}

private void insertDirectDistanceTrigger(DirectTriggerData data, Vector3dc cameraPos, double remainingDistance) {
this.insertJitteredTrigger(this.accumulatedDistance + remainingDistance, data);
this.insertTrigger(this.accumulatedDistance + remainingDistance, data);
}

// TODO: instead of jittering use Tree<Object> where object is either a list or
// an individual record?
// jitters the double values to never overwrite the same key. abuses that
// doubles have more precision than we need to make them a kind of hash table
private double lastJittered = -1;
private double lastJitterResult = -1;

private void insertJitteredTrigger(double key, DirectTriggerData data) {
// attempt insert without jittering
if (this.directTriggerSections.putIfAbsent(key, data) == null) {
data.dynamicData.directTriggerKey = key;
return;
}

// if this is the same key as last time, skip all the identical keys that have
// already been jittered
if (this.lastJittered == key) {
key = this.lastJitterResult;
} else {
this.lastJittered = key;
}

// Go to the next lower double to avoid collisions in the map. This slightly
// changes the key but doesn't significantly change its value. Subtraction is
// necessary to avoid delaying a trigger for too long. It's ok if it's too early
// though. This approach brings with it the disadvantages of linear probing but
// bad cases are unlikely to happen so it's fine.
do {
key = Math.nextDown(key);
} while (this.directTriggerSections.putIfAbsent(key, data) != null);
private void insertTrigger(double key, DirectTriggerData data) {
data.dynamicData.directTriggerKey = key;
this.lastJitterResult = key;

// attach the previous value after the current one in the list. if there is none
// it's just null
data.next = this.directTriggerSections.put(key, data);
}

@Override
Expand All @@ -159,43 +134,49 @@ public void processTriggers(TranslucentSorting ts, CameraMovement movement) {
var head = this.directTriggerSections.headMap(this.accumulatedDistance);
for (var entry : head.double2ObjectEntrySet()) {
this.directTriggerSections.remove(entry.getDoubleKey());
DirectTriggerData data = entry.getValue();

boolean isAngle = data.isAngleTriggering(camera);
if (isAngle) {
double remainingAngle = TRIGGER_ANGLE;

// check if the angle since the last sort exceeds the threshold
Vector3dc sectionCenter = data.getSectionCenter();
double angleCos = angleCos(
sectionCenter.x() - data.triggerCameraPos.x(),
sectionCenter.y() - data.triggerCameraPos.y(),
sectionCenter.z() - data.triggerCameraPos.z(),
sectionCenter.x() - camera.x(),
sectionCenter.y() - camera.y(),
sectionCenter.z() - camera.z());

// compare angles inverted because cosine flips it
if (angleCos <= EARLY_TRIGGER_ANGLE_COS) {
ts.triggerSectionDirect(data.sectionPos);
data.triggerCameraPos = camera;
var data = entry.getValue();
while (data != null) {
// get the next element before it's modified by the data being re-inserted into
// the tree
var next = data.next;

if (data.isAngleTriggering(camera)) {
double remainingAngle = TRIGGER_ANGLE;

// check if the angle since the last sort exceeds the threshold
Vector3dc sectionCenter = data.getSectionCenter();
double angleCos = angleCos(
sectionCenter.x() - data.triggerCameraPos.x(),
sectionCenter.y() - data.triggerCameraPos.y(),
sectionCenter.z() - data.triggerCameraPos.z(),
sectionCenter.x() - camera.x(),
sectionCenter.y() - camera.y(),
sectionCenter.z() - camera.z());

// compare angles inverted because cosine flips it
if (angleCos <= EARLY_TRIGGER_ANGLE_COS) {
ts.triggerSectionDirect(data.sectionPos);
data.triggerCameraPos = camera;
} else {
remainingAngle -= Math.acos(angleCos);
}

this.insertDirectAngleTrigger(data, camera, remainingAngle);
} else {
remainingAngle -= Math.acos(angleCos);
}
double remainingDistance = DIRECT_TRIGGER_DISTANCE;
double lastTriggerCurrentCameraDistSquared = data.triggerCameraPos.distanceSquared(camera);

this.insertDirectAngleTrigger(data, camera, remainingAngle);
} else {
double remainingDistance = DIRECT_TRIGGER_DISTANCE;
double lastTriggerCurrentCameraDistSquared = data.triggerCameraPos.distanceSquared(camera);
if (lastTriggerCurrentCameraDistSquared >= EARLY_DIRECT_TRIGGER_DISTANCE_SQUARED) {
ts.triggerSectionDirect(data.sectionPos);
data.triggerCameraPos = camera;
} else {
remainingDistance -= Math.sqrt(lastTriggerCurrentCameraDistSquared);
}

if (lastTriggerCurrentCameraDistSquared >= EARLY_DIRECT_TRIGGER_DISTANCE_SQUARED) {
ts.triggerSectionDirect(data.sectionPos);
data.triggerCameraPos = camera;
} else {
remainingDistance -= Math.sqrt(lastTriggerCurrentCameraDistSquared);
this.insertDirectDistanceTrigger(data, camera, remainingDistance);
}

this.insertDirectDistanceTrigger(data, camera, remainingDistance);
data = next;
}
}
}
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