void clRasterizer::DrawTri(clList<Fragment> *pFragList, const clVec2 &v1, const clVec2 &v2, const clVec2 &v3)
{
  Fragment f1(v1, 0);
  Fragment f2(v2, 1);
  Fragment f3(v3, 2);
  Span s[3] = { Span(f1, f2) , Span(f2, f3), Span(f3, f1) };
  if (s[2].Length() > s[1].Length()) clSwap(s[1], s[2]);
  if (s[1].Length() > s[0].Length()) clSwap(s[0], s[1]);
  DrawSpan(pFragList, s[0], s[1]);
  DrawSpan(pFragList, s[0], s[2]);
}

void clRasterizer::DrawSpan(clList<Fragment> *pFragList, const Span &longSpan, const Span &shortSpan)
{
  clVec2 shortLine = shortSpan.PositionDelta();
  clVec2 longLine = longSpan.PositionDelta();
  if (shortLine.y == 0 || longLine.y == 0) return; // Skip if span is empty

  float shortTop = shortSpan.m_f1.m_position.y; // Calculate Spans Vertical Extents
  float shortBot = shortSpan.m_f2.m_position.y;
  i64 yTop = (i64)ceil(shortTop);
  i64 yBot = (i64)ceil(shortBot);

  float shortStepX = (shortLine.x / shortLine.y); // Calculate Spans Stepping rates
  float longStepX = (longLine.x / longLine.y);
  clVec3 shortStepInf = (shortSpan.m_f2.m_influence - shortSpan.m_f1.m_influence) / shortLine.y;
  clVec3 longStepInf = (longSpan.m_f2.m_influence - longSpan.m_f1.m_influence) / longLine.y;

  float longStart = (shortTop - longSpan.m_f1.m_position.y) / longLine.y; // Calculate long edge start pos

  float shortPosX = shortSpan.m_f1.m_position.x; // Calculate the Scans Initial xPosition
  float longPosX = longSpan.m_f1.m_position.x * (1.0f - longStart) + longSpan.m_f2.m_position.x * (longStart);

  clVec3 shortInf = shortSpan.m_f1.m_influence; // Calculate the Scans Initial Influence
  clVec3 longInf = longSpan.m_f1.m_influence * (1.0f - longStart) + longSpan.m_f2.m_influence * (longStart);

  float fillOffset = (yTop - shortTop); // Apply OpenGLs fragment filling conventions
  shortPosX += shortStepX * fillOffset;
  longPosX += longStepX * fillOffset;
  shortInf += shortStepInf * fillOffset;
  longInf += longStepInf * fillOffset;

  for (i64 y = yTop; y < yBot; y++) // Draw all Scans in Span
  {
    Fragment shortEdge({ shortPosX, (float)y }, shortInf);
    Fragment longEdge({ longPosX, (float)y }, longInf);
    DrawScan(pFragList, { shortEdge, longEdge });
    shortPosX += shortStepX;
    longPosX += longStepX;
    shortInf += shortStepInf;
    longInf += longStepInf;
  }
}

void clRasterizer::DrawScan(clList<Fragment> *pFragList, const Scan &scan)
{
  i64 leftPosX = (i64)(clFloor(scan.m_f1.m_position.x)); // Calculate Scan line Extents
  i64 rightPosX = (i64)(clCeil(scan.m_f2.m_position.x));
  i64 posY = (i64)scan.m_f1.m_position.y;
  clVec3 influence = scan.m_f1.m_influence; // Calculate Stepping Rates
  clVec3 stepInfluence = (scan.m_f2.m_influence - scan.m_f1.m_influence) / (float(rightPosX) - leftPosX);
  for (i64 x = leftPosX; x < rightPosX; x++) // Draw all fragments in Scan
  {
    pFragList->EmplaceBack(clVec2((float)x, (float)posY), influence);
    influence += stepInfluence;
  }
}