Implement bezier lines.
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parent
502eb95278
commit
16bb3f41a7
@ -1,5 +1,4 @@
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using System;
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using Quik.VertexGenerator;
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namespace Quik
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{
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@ -153,6 +152,38 @@ namespace Quik
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/// </summary>
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public QuikVec2 End;
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/// <summary>
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/// An approximation of the arc length of the bezier curve, for calculating rasterization resolution.
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/// </summary>
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public float RasterizationArc =>
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0.5f * (End - Start).Magnitude +
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0.5f * ((ControlA - Start).Magnitude + (ControlB - ControlA).Magnitude + (End - ControlB).Magnitude);
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public QuikBezier(QuikVec2 start, QuikVec2 controlA, QuikVec2 controlB, QuikVec2 end)
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{
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Start = start;
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ControlA = controlA;
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ControlB = controlB;
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End = end;
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}
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public QuikBezier(
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float startX,
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float startY,
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float controlAx,
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float controlAy,
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float controlBx,
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float controlBy,
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float endX,
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float endY)
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: this(
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new QuikVec2(startX, startY),
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new QuikVec2(controlAx, controlAy),
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new QuikVec2(controlBx, controlBy),
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new QuikVec2(endX, endY))
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{
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}
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/// <summary>
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/// Get a point in the curve segment.
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/// </summary>
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@ -160,11 +191,12 @@ namespace Quik
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/// <returns>The point on the curve.</returns>
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public QuikVec2 GetBezierPoint(float t)
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{
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float T = 1 - t;
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return
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(1 - t) * (1 - t) * (1 - t) * Start +
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(1 - t) * (1 - t) * t * ControlA +
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(1 - t) * t * t * ControlB +
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t * t * t * End;
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T * T * T * Start +
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3 * T * T * t * ControlA +
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3 * T * t * t * ControlB +
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t * t * t * End;
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}
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/// <summary>
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@ -174,10 +206,11 @@ namespace Quik
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/// <returns>The tangent curve.</returns>
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public QuikVec2 GetBezierTangent(float t)
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{
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float T = 1 - t;
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return
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3 * (1 - t) * (1 - t) * (ControlA - Start) +
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6 * (1 - t) * (ControlB - ControlA) +
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3 * t * t * (End - ControlB);
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3 * T * T * (ControlA - Start) +
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6 * T * t * (ControlB - ControlA) +
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3 * t * t * (End - ControlB);
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}
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}
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@ -65,7 +65,7 @@ namespace Quik.VertexGenerator
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/// </summary>
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public int ElementCount => _elementBufferPointer;
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public float CurveGranularity { get; set; } = 0.5f;
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public float CurveGranularity { get; set; } = 0.2f;
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public QuikContext Context { get; }
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@ -186,6 +186,9 @@ namespace Quik.VertexGenerator
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case QuikCommandType.Lines:
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RenderLine(ref call, command as QuikCommandLines);
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return call;
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case QuikCommandType.Bezier:
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RenderBezier(ref call, command as QuikCommandBezier);
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return call;
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}
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return null;
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}
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@ -502,7 +505,8 @@ namespace Quik.VertexGenerator
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}
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else
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{
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// There is no need to generate anything because the lines are the same???
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// There is a cusp. Generate an end cap.
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GenerateEndCap(baseVertex, focus, prevNormal.Normalize(), width, GetRoundingResolution(width, MathF.PI), prevPositiveEndIndex, prevNegativeEndIndex);
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}
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}
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@ -595,6 +599,134 @@ namespace Quik.VertexGenerator
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call.Offset = (short) (startOffset * 2);
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call.Count = (short) (_elementBufferPointer - startOffset);
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}
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private void RenderBezier(ref QuikDrawCall call, QuikCommandBezier bezier)
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{
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QuikStrokeStyle style = bezier.Style ?? Context.DefaultStroke;
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QuikVertex baseVertex = new QuikVertex() { Color = style.Color };
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bool isStart;
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bool isEnd;
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short startOffset = (short)_elementBufferPointer;
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int capResolution = GetRoundingResolution(style.Width, MathF.PI);
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short lastEndPositive = 0;
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short lastEndNegative = 0;
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for (int i = 0; i < bezier.Segments.Length; i++)
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{
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QuikBezier segment = bezier.Segments[i];
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isStart = i == 0 || segment.Start != bezier.Segments[i - 1].End;
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isEnd = i == bezier.Segments.Length - 1 || segment.End != bezier.Segments[i + 1].Start;
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GenerateBezierSegment(
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baseVertex,
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segment,
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style.Width,
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out short startPositive,
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out short startNegative,
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out short endPositive,
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out short endNegative,
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out QuikVec2 startNormal,
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out QuikVec2 endNormal);
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if (isStart)
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{
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GenerateStartCap(baseVertex, segment.Start, startNormal, style.Width, capResolution,
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startPositive, startNegative);
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}
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else
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{
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GenerateJoint(
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baseVertex,
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segment.Start,
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bezier.Segments[i-1].GetBezierTangent(1),
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segment.GetBezierTangent(0),
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style.Width,
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lastEndPositive,
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lastEndNegative,
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startPositive,
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startNegative
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);
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}
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if (isEnd)
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{
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GenerateEndCap(
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baseVertex,
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segment.End,
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endNormal,
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style.Width,
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capResolution,
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endPositive,
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endNegative
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);
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}
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lastEndPositive = endPositive;
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lastEndNegative = endNegative;
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}
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call.Offset = (short) (startOffset * 2);
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call.Count = (short) (_elementBufferPointer - startOffset);
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}
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private void GenerateBezierSegment(
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QuikVertex baseVertex,
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QuikBezier bezier,
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float width,
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out short startPositiveIndex,
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out short startNegativeIndex,
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out short endPositiveIndex,
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out short endNegativeIndex,
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out QuikVec2 startNormal,
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out QuikVec2 endNormal)
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{
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QuikVec2 startTangent = bezier.GetBezierTangent(0);
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QuikVec2 endTangent = bezier.GetBezierTangent(1);
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startNormal = new QuikVec2(-startTangent.Y, startTangent.X).Normalize();
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endNormal = new QuikVec2(-endTangent.Y, endTangent.X).Normalize();
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int resolution = GetRoundingResolution(width, bezier.RasterizationArc);
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startPositiveIndex = (short)_vertexBufferPointer;
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startNegativeIndex = (short) (startPositiveIndex + 1);
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QuikVertex startPositive = baseVertex;
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QuikVertex startNegative = baseVertex;
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startPositive.Position = bezier.Start + 0.5f * width * startNormal;
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startNegative.Position = bezier.Start - 0.5f * width * startNormal;
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AddVertex(startPositive, startNegative);
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for (int i = 0; i < resolution; i++)
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{
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float t = (float) (i + 1) / resolution;
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QuikVec2 at = bezier.GetBezierTangent(t).Normalize();
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QuikVec2 a = bezier.GetBezierPoint(t);
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QuikVec2 an = 0.5f * width * new QuikVec2(-at.Y, at.X);
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short index = (short) _vertexBufferPointer;
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QuikVertex apv = baseVertex, anv = baseVertex;
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apv.Position = a + an;
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anv.Position = a - an;
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AddVertex(apv, anv);
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AddElement(
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(short)(index - 2),
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(short)(index - 1),
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(short)(index + 0),
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(short)(index - 1),
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(short)(index + 1),
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(short)(index + 0));
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}
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endNegativeIndex = (short) (_vertexBufferPointer - 1);
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endPositiveIndex = (short) (_vertexBufferPointer - 2);
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}
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}
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public enum QuikRenderTarget
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@ -155,6 +155,11 @@ void main()
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new QuikLine(64, 30, 64, 10),
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new QuikLine(64, 10, 74, 10)
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);
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context.Draw.Bezier(
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new QuikBezier(46, 10, 56, 10, 46, 30, 56, 30),
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new QuikBezier(56, 30, 46, 30, 56, 60, 46, 60),
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new QuikBezier(46, 60, 56, 60, 46, 90, 56, 90));
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QuikCommand command;
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while (context.Draw.Commands.TryDequeue(out command))
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