skgpu::tess::MiddleOutPolygonTriangulator Class Reference

#include <MiddleOutPolygonTriangulator.h>

Classes
class	PoppedTriangleStack

Public Member Functions
	MiddleOutPolygonTriangulator (int maxPushVertexCalls, SkPoint startPoint={0, 0})
PoppedTriangleStack	pushVertex (SkPoint pt)
PoppedTriangleStack	closeAndMove (SkPoint newStartPoint)
PoppedTriangleStack	close ()

Detailed Description

Definition at line 52 of file MiddleOutPolygonTriangulator.h.

Constructor & Destructor Documentation

MiddleOutPolygonTriangulator()

skgpu::tess::MiddleOutPolygonTriangulator::MiddleOutPolygonTriangulator ( int  maxPushVertexCalls, SkPoint  startPoint = {0,0}  )

inline

Definition at line 127 of file MiddleOutPolygonTriangulator.h.

                                                                              {0,0}) {
        SkASSERT(maxPushVertexCalls >= 0);
        // Determine the deepest our stack can ever go.
        int maxStackDepth = SkNextLog2(maxPushVertexCalls) + 1;
        if (maxStackDepth > kStackPreallocCount) {
            fVertexStack.reset(maxStackDepth);
        }
        SkDEBUGCODE(fStackAllocCount = maxStackDepth;)
        // The stack will always contain a starting point. This is an implicit moveTo(0, 0)
        // initially, but will be overridden if moveTo() gets called before adding geometry.
        fVertexStack[0] = {startPoint, 0};
        fTop = fVertexStack;
    }

Member Function Documentation

close()

PoppedTriangleStack skgpu::tess::MiddleOutPolygonTriangulator::close ( )

inline

Definition at line 187 of file MiddleOutPolygonTriangulator.h.

                                              {
        return this->closeAndMove(fVertexStack[0].fPoint);
    }

closeAndMove()

PoppedTriangleStack skgpu::tess::MiddleOutPolygonTriangulator::closeAndMove ( SkPoint  newStartPoint )

inline

Definition at line 170 of file MiddleOutPolygonTriangulator.h.

                                                                          {
        // Add an implicit line back to the starting point.
        SkPoint startPt = fVertexStack[0].fPoint;
 
        // Triangulate the rest of the polygon. Since we simply have to finish now, we can't be
        // picky anymore about getting a pure middle-out topology.
        StackVertex* endVertex = std::min(fTop, fVertexStack + 1);
 
        // Once every remaining triangle is popped, reset the vertex stack with newStartPoint.
        StackVertex* newTopVertex = fVertexStack;
        StackVertex newTopValue = {newStartPoint, 0};
 
        return PoppedTriangleStack(this, startPt, endVertex, newTopVertex, newTopValue);
    }

pushVertex()

PoppedTriangleStack skgpu::tess::MiddleOutPolygonTriangulator::pushVertex ( SkPoint  pt )

inline

Definition at line 143 of file MiddleOutPolygonTriangulator.h.

                                                             {
        // Our topology wants triangles that have the same vertexIdxDelta on both sides:
        // e.g., a run of 9 points should be triangulated as:
        //
        //    [0, 1, 2], [2, 3, 4], [4, 5, 6], [6, 7, 8]  // vertexIdxDelta == 1
        //    [0, 2, 4], [4, 6, 8]  // vertexIdxDelta == 2
        //    [0, 4, 8]  // vertexIdxDelta == 4
        //
        // Find as many new triangles as we can pop off the stack that have equal-delta sides. (This
        // is a stack-based implementation of the recursive example method from the class comment.)
        StackVertex* endVertex = fTop;
        int vertexIdxDelta = 1;
        while (endVertex->fVertexIdxDelta == vertexIdxDelta) {
            --endVertex;
            vertexIdxDelta *= 2;
        }
 
        // Once the above triangles are popped, push 'pt' to the top of the stack.
        StackVertex* newTopVertex = endVertex + 1;
        StackVertex newTopValue = {pt, vertexIdxDelta};
        SkASSERT(newTopVertex < fVertexStack + fStackAllocCount); // Is fStackAllocCount enough?
 
        return PoppedTriangleStack(this, pt, endVertex, newTopVertex, newTopValue);
    }

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The documentation for this class was generated from the following file:

• third_party/skia/src/gpu/tessellate/MiddleOutPolygonTriangulator.h