void UPaperTerrainComponent::InsertConvexCollisionDataFromPolygon(const TArray<FVector2D>& ClosedPolyVertices2D)
{
if (CachedBodySetup != nullptr && ClosedPolyVertices2D.Num() >= 3)
{
// Simplify polygon
TArray<float> EmptyOffsetsList;
TArray<FVector2D> LocalPolyVertices = ClosedPolyVertices2D;
SimplifyPolygon(LocalPolyVertices, EmptyOffsetsList);
// Always CCW and facing forward regardless of spline winding
TArray<FVector2D> CorrectedSplineVertices;
PaperGeomTools::CorrectPolygonWinding(CorrectedSplineVertices, LocalPolyVertices, false);
TArray<FVector2D> TriangulatedPolygonVertices;
PaperGeomTools::TriangulatePoly(/*out*/TriangulatedPolygonVertices, CorrectedSplineVertices, false);
TArray<TArray<FVector2D>> ConvexHulls;
PaperGeomTools::GenerateConvexPolygonsFromTriangles(ConvexHulls, TriangulatedPolygonVertices);
for (TArray<FVector2D> ConvexHull : ConvexHulls)
{
FKConvexElem Convex;
for (int J = 0; J < ConvexHull.Num(); ++J)
{
FVector2D& Vert = ConvexHull[J];
new(Convex.VertexData) FVector(Vert.X, -0.5f * CollisionThickness, Vert.Y);
new(Convex.VertexData) FVector(Vert.X, 0.5f * CollisionThickness, Vert.Y);
}
Convex.UpdateElemBox();
CachedBodySetup->AggGeom.ConvexElems.Add(Convex);
}
}
}
void UPaperTerrainComponent::InsertConvexCollisionDataFromPolygon(const TArray<FVector2D>& ClosedPolyVertices2D)
{
if (CachedBodySetup != nullptr && ClosedPolyVertices2D.Num() >= 3)
{
// Simplify polygon
TArray<float> EmptyOffsetsList;
TArray<FVector2D> LocalPolyVertices = ClosedPolyVertices2D;
// The merge / weld threshold should not be any lower / less than half the thickness
float PolygonThickness = (ClosedPolyVertices2D[0] - ClosedPolyVertices2D[ClosedPolyVertices2D.Num() - 1]).Size();
float SimplifyThreshold = PolygonThickness * 0.5f;
SimplifyPolygon(LocalPolyVertices, EmptyOffsetsList, SimplifyThreshold);
// Always CCW and facing forward regardless of spline winding
TArray<FVector2D> CorrectedSplineVertices;
PaperGeomTools::CorrectPolygonWinding(CorrectedSplineVertices, LocalPolyVertices, false);
TArray<FVector2D> TriangulatedPolygonVertices;
if (!PaperGeomTools::TriangulatePoly(/*out*/TriangulatedPolygonVertices, CorrectedSplineVertices, false))
{
// Triangulation failed, try triangulating the original non simplified polygon
CorrectedSplineVertices.Empty();
PaperGeomTools::CorrectPolygonWinding(/*out*/CorrectedSplineVertices, ClosedPolyVertices2D, false);
TriangulatedPolygonVertices.Empty();
PaperGeomTools::TriangulatePoly(/*out*/TriangulatedPolygonVertices, CorrectedSplineVertices, false);
}
TArray<TArray<FVector2D>> ConvexHulls;
PaperGeomTools::GenerateConvexPolygonsFromTriangles(ConvexHulls, TriangulatedPolygonVertices);
for (TArray<FVector2D> ConvexHull : ConvexHulls)
{
FKConvexElem Convex;
for (int J = 0; J < ConvexHull.Num(); ++J)
{
FVector2D& Vert = ConvexHull[J];
new(Convex.VertexData) FVector(Vert.X, -0.5f * CollisionThickness, Vert.Y);
new(Convex.VertexData) FVector(Vert.X, 0.5f * CollisionThickness, Vert.Y);
}
Convex.UpdateElemBox();
CachedBodySetup->AggGeom.ConvexElems.Add(Convex);
}
}
}
void UPaperTerrainComponent::OnSplineEdited()
{
// Ensure we have the data structure for the desired collision method
if (SpriteCollisionDomain == ESpriteCollisionMode::Use3DPhysics)
{
CachedBodySetup = NewObject<UBodySetup>(this);
}
else
{
CachedBodySetup = nullptr;
}
const float SlopeAnalysisTimeRate = 10.0f;
const float FillRasterizationTimeRate = 100.0f;
GeneratedSpriteGeometry.Empty();
if ((AssociatedSpline != nullptr) && (TerrainMaterial != nullptr))
{
if (AssociatedSpline->ReparamStepsPerSegment != ReparamStepsPerSegment)
{
AssociatedSpline->ReparamStepsPerSegment = ReparamStepsPerSegment;
AssociatedSpline->UpdateSpline();
}
FRandomStream RandomStream(RandomSeed);
const FInterpCurveVector& SplineInfo = AssociatedSpline->SplineInfo;
float SplineLength = AssociatedSpline->GetSplineLength();
struct FTerrainRuleHelper
{
public:
FTerrainRuleHelper(const FPaperTerrainMaterialRule* Rule)
: StartWidth(0.0f)
, EndWidth(0.0f)
{
for (const UPaperSprite* Sprite : Rule->Body)
{
if (Sprite != nullptr)
{
const float Width = GetSpriteRenderDataBounds2D(Sprite->BakedRenderData).GetSize().X;
if (Width > 0.0f)
{
ValidBodies.Add(Sprite);
ValidBodyWidths.Add(Width);
}
}
}
if (Rule->StartCap != nullptr)
{
const float Width = GetSpriteRenderDataBounds2D(Rule->StartCap->BakedRenderData).GetSize().X;
if (Width > 0.0f)
{
StartWidth = Width;
}
}
if (Rule->EndCap != nullptr)
{
const float Width = GetSpriteRenderDataBounds2D(Rule->EndCap->BakedRenderData).GetSize().X;
if (Width > 0.0f)
{
EndWidth = Width;
}
}
}
float StartWidth;
float EndWidth;
TArray<const UPaperSprite*> ValidBodies;
TArray<float> ValidBodyWidths;
int32 GenerateBodyIndex(FRandomStream& InRandomStream) const
{
check(ValidBodies.Num() > 0);
return InRandomStream.GetUnsignedInt() % ValidBodies.Num();
}
};
// Split the spline into segments based on the slope rules in the material
TArray<FTerrainSegment> Segments;
FTerrainSegment* ActiveSegment = new (Segments) FTerrainSegment();
ActiveSegment->StartTime = 0.0f;
ActiveSegment->EndTime = SplineLength;
{
float CurrentTime = 0.0f;
while (CurrentTime < SplineLength)
{
const FTransform Frame(GetTransformAtDistance(CurrentTime));
const FVector UnitTangent = Frame.GetUnitAxis(EAxis::X);
const float RawSlopeAngleRadians = FMath::Atan2(FVector::DotProduct(UnitTangent, PaperAxisY), FVector::DotProduct(UnitTangent, PaperAxisX));
const float RawSlopeAngle = FMath::RadiansToDegrees(RawSlopeAngleRadians);
const float SlopeAngle = FMath::Fmod(FMath::UnwindDegrees(RawSlopeAngle) + 360.0f, 360.0f);
const FPaperTerrainMaterialRule* DesiredRule = (TerrainMaterial->Rules.Num() > 0) ? &(TerrainMaterial->Rules[0]) : nullptr;
for (const FPaperTerrainMaterialRule& TestRule : TerrainMaterial->Rules)
{
if ((SlopeAngle >= TestRule.MinimumAngle) && (SlopeAngle < TestRule.MaximumAngle))
{
DesiredRule = &TestRule;
}
}
if (ActiveSegment->Rule != DesiredRule)
{
if (ActiveSegment->Rule == nullptr)
{
ActiveSegment->Rule = DesiredRule;
}
else
{
ActiveSegment->EndTime = CurrentTime;
// Segment is too small, delete it
if (ActiveSegment->EndTime < ActiveSegment->StartTime + 2.0f * SegmentOverlapAmount)
{
Segments.Pop(false);
}
ActiveSegment = new (Segments)FTerrainSegment();
ActiveSegment->StartTime = CurrentTime;
ActiveSegment->EndTime = SplineLength;
ActiveSegment->Rule = DesiredRule;
}
}
CurrentTime += SlopeAnalysisTimeRate;
}
}
// Account for overlap
for (FTerrainSegment& Segment : Segments)
{
Segment.StartTime -= SegmentOverlapAmount;
Segment.EndTime += SegmentOverlapAmount;
}
// Convert those segments to actual geometry
for (FTerrainSegment& Segment : Segments)
{
check(Segment.Rule);
FTerrainRuleHelper RuleHelper(Segment.Rule);
float RemainingSegStart = Segment.StartTime + RuleHelper.StartWidth;
float RemainingSegEnd = Segment.EndTime - RuleHelper.EndWidth;
const float BodyDistance = RemainingSegEnd - RemainingSegStart;
float DistanceBudget = BodyDistance;
bool bUseBodySegments = (DistanceBudget > 0.0f) && (RuleHelper.ValidBodies.Num() > 0);
// Add the start cap
if (RuleHelper.StartWidth > 0.0f)
{
new (Segment.Stamps) FTerrainSpriteStamp(Segment.Rule->StartCap, Segment.StartTime + RuleHelper.StartWidth * 0.5f, /*bIsEndCap=*/ bUseBodySegments);
}
// Add body segments
if (bUseBodySegments)
{
int32 NumSegments = 0;
float Position = RemainingSegStart;
while (DistanceBudget > 0.0f)
{
const int32 BodyIndex = RuleHelper.GenerateBodyIndex(RandomStream);
const UPaperSprite* Sprite = RuleHelper.ValidBodies[BodyIndex];
const float Width = RuleHelper.ValidBodyWidths[BodyIndex];
if ((NumSegments > 0) && ((Width * 0.5f) > DistanceBudget))
{
break;
}
new (Segment.Stamps) FTerrainSpriteStamp(Sprite, Position + (Width * 0.5f), /*bIsEndCap=*/ false);
DistanceBudget -= Width;
Position += Width;
++NumSegments;
}
const float UsedSpace = (BodyDistance - DistanceBudget);
const float OverallScaleFactor = BodyDistance / UsedSpace;
// Stretch body segments
float PositionCorrectionSum = 0.0f;
for (int32 Index = 0; Index < NumSegments; ++Index)
{
FTerrainSpriteStamp& Stamp = Segment.Stamps[Index + (Segment.Stamps.Num() - NumSegments)];
const float WidthChange = (OverallScaleFactor - 1.0f) * Stamp.NominalWidth;
const float FirstGapIsSmallerFactor = (Index == 0) ? 0.5f : 1.0f;
PositionCorrectionSum += WidthChange * FirstGapIsSmallerFactor;
Stamp.Scale = OverallScaleFactor;
Stamp.Time += PositionCorrectionSum;
}
}
else
{
// Stretch endcaps
}
// Add the end cap
if (RuleHelper.EndWidth > 0.0f)
{
new (Segment.Stamps) FTerrainSpriteStamp(Segment.Rule->EndCap, Segment.EndTime - RuleHelper.EndWidth * 0.5f, /*bIsEndCap=*/ bUseBodySegments);
}
}
// Convert stamps into geometry
SpawnSegments(Segments, !bClosedSpline || (bClosedSpline && !bFilledSpline));
// Generate the background if the spline is closed
if (bClosedSpline && bFilledSpline)
{
// Create a polygon from the spline
FBox2D SplineBounds(ForceInit);
TArray<FVector2D> SplinePolyVertices2D;
TArray<float> SplineEdgeOffsetAmounts;
{
float CurrentTime = 0.0f;
while (CurrentTime < SplineLength)
{
const float Param = AssociatedSpline->SplineReparamTable.Eval(CurrentTime, 0.0f);
const FVector Position3D = AssociatedSpline->SplineInfo.Eval(Param, FVector::ZeroVector);
const FVector2D Position2D = FVector2D(FVector::DotProduct(Position3D, PaperAxisX), FVector::DotProduct(Position3D, PaperAxisY));
SplineBounds += Position2D;
SplinePolyVertices2D.Add(Position2D);
// Find the collision offset for this sample point
float CollisionOffset = 0;
for (int SegmentIndex = 0; SegmentIndex < Segments.Num(); ++SegmentIndex)
{
FTerrainSegment& Segment = Segments[SegmentIndex];
if (CurrentTime >= Segment.StartTime && CurrentTime <= Segment.EndTime)
{
CollisionOffset = (Segment.Rule != nullptr) ? (Segment.Rule->CollisionOffset * 0.25f) : 0;
break;
}
}
SplineEdgeOffsetAmounts.Add(CollisionOffset);
CurrentTime += FillRasterizationTimeRate;
}
}
SimplifyPolygon(SplinePolyVertices2D, SplineEdgeOffsetAmounts);
// Always CCW and facing forward regardless of spline winding
TArray<FVector2D> CorrectedSplineVertices;
PaperGeomTools::CorrectPolygonWinding(CorrectedSplineVertices, SplinePolyVertices2D, false);
TArray<FVector2D> TriangulatedPolygonVertices;
PaperGeomTools::TriangulatePoly(/*out*/TriangulatedPolygonVertices, CorrectedSplineVertices, false);
GenerateCollisionDataFromPolygon(SplinePolyVertices2D, SplineEdgeOffsetAmounts, TriangulatedPolygonVertices);
if (TerrainMaterial->InteriorFill != nullptr)
{
const UPaperSprite* FillSprite = TerrainMaterial->InteriorFill;
FPaperTerrainSpriteGeometry& MaterialBatch = *new (GeneratedSpriteGeometry)FPaperTerrainSpriteGeometry(); //@TODO: Look up the existing one instead
MaterialBatch.Material = FillSprite->GetDefaultMaterial();
FSpriteDrawCallRecord& FillDrawCall = *new (MaterialBatch.Records) FSpriteDrawCallRecord();
FillDrawCall.BuildFromSprite(FillSprite);
FillDrawCall.RenderVerts.Empty();
FillDrawCall.Color = TerrainColor;
FillDrawCall.Destination = PaperAxisZ * 0.1f;
const FVector2D TextureSize = GetSpriteRenderDataBounds2D(FillSprite->BakedRenderData).GetSize();
const FVector2D SplineSize = SplineBounds.GetSize();
GenerateFillRenderDataFromPolygon(FillSprite, FillDrawCall, TextureSize, TriangulatedPolygonVertices);
//@TODO: Add support for the fill sprite being smaller than the entire texture
#if NOT_WORKING
const float StartingDivisionPointX = FMath::CeilToFloat(SplineBounds.Min.X / TextureSize.X);
const float StartingDivisionPointY = FMath::CeilToFloat(SplineBounds.Min.Y / TextureSize.Y);
FPoly VerticalRemainder = SplineAsPolygon;
for (float Y = StartingDivisionPointY; VerticalRemainder.Vertices.Num() > 0; Y += TextureSize.Y)
{
FPoly Top;
FPoly Bottom;
const FVector SplitBaseOuter = (Y * PaperAxisY);
VerticalRemainder.SplitWithPlane(SplitBaseOuter, -PaperAxisY, &Top, &Bottom, 1);
VerticalRemainder = Bottom;
FPoly HorizontalRemainder = Top;
for (float X = StartingDivisionPointX; HorizontalRemainder.Vertices.Num() > 0; X += TextureSize.X)
{
FPoly Left;
FPoly Right;
const FVector SplitBaseInner = (X * PaperAxisX) + (Y * PaperAxisY);
HorizontalRemainder.SplitWithPlane(SplitBaseInner, -PaperAxisX, &Left, &Right, 1);
HorizontalRemainder = Right;
//BROKEN, function no longer exists (split into 2 parts)
SpawnFromPoly(Segments, SplineEdgeOffsetAmounts, FillSprite, FillDrawCall, TextureSize, Left);
}
}
#endif
}
}
// Draw debug frames at the start and end of the spline
#if PAPER_TERRAIN_DRAW_DEBUG
{
const float Time = 5.0f;
{
FTransform WorldTransform = GetTransformAtDistance(0.0f) * ComponentToWorld;
DrawDebugCoordinateSystem(GetWorld(), WorldTransform.GetLocation(), FRotator(WorldTransform.GetRotation()), 30.0f, true, Time, SDPG_Foreground);
}
{
FTransform WorldTransform = GetTransformAtDistance(SplineLength) * ComponentToWorld;
DrawDebugCoordinateSystem(GetWorld(), WorldTransform.GetLocation(), FRotator(WorldTransform.GetRotation()), 30.0f, true, Time, SDPG_Foreground);
}
}
#endif
}
RecreateRenderState_Concurrent();
}
