NL3D::CQuadEffect Class Reference

#include <quad_effect.h>

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Detailed Description

This class allow to create a sequence of small quads that tesselate a poly.

Author:

Nicolas Vizerie

Nevrax France

Date:

2001

Definition at line 46 of file quad_effect.h.

Public Types
typedef std::vector< NLMISC::CVector2f >	TPoint2DVect
	a vector of 2d points
typedef std::vector< std::pair< float, float > >	TRasters
Static Public Member Functions
void	makeRasters (const TPoint2DVect &poly, float quadWidth, float quadHeight, TRasters &dest, float &startY)
void	processPoly (const TPoint2DVect &poly, float quadWidth, float quadHeight, TPoint2DVect &dest)

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Member Typedef Documentation

typedef std::vector<NLMISC::CVector2f> NL3D::CQuadEffect::TPoint2DVect

a vector of 2d points Definition at line 50 of file quad_effect.h.

typedef std::vector< std::pair< float, float> > NL3D::CQuadEffect::TRasters

Definition at line 53 of file quad_effect.h. Referenced by makeRasters(), and processPoly().

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Member Function Documentation

void NL3D::CQuadEffect::makeRasters (  const TPoint2DVect &  poly, float  quadWidth, float  quadHeight, TRasters &  dest, float &  startY )  [static]

Make raters from the given clipped polygon. Parameters: poly  a polygon that describe the area where datas are taken from. quadWidth  width of the quad quadHeight  height of the quad dest  a vector that will be filled with the given rasters startY  will be filled with the start y position on screen edge is in scope. compute its extreme positions so we need to intersect it with the y = currY and y = currY + quadHeight lines Definition at line 61 of file quad_effect.cpp. References min, sint, size, NL3D::TEdgeList, TRasters, and uint. Referenced by processPoly(). { dest.clear(); const float epsilon = 10E-5f; sint size = poly.size(); uint aelSize = 0; // size of active edge list sint k; // loop counter dest.clear(); if (!size) return; static TEdgeList lel, ael; // the left edge list, and the active edge list float highest = poly[0].y; lel.clear(); ael.clear(); for (k = 0; k < size; ++k) { lel.push_front( CEdge(poly[k], poly[k == (size - 1) ? 0 : k + 1]) ); if (poly[k].y < highest) { highest = poly[k].y; } } std::sort(lel.begin(), lel.end()); bool borderFound; float left, right, inter, diff; float currY = highest; startY = highest; TEdgeList::iterator elIt; do { while (size && lel.begin()->P1.y < (currY + quadHeight) ) { ael.push_front(lel.front()); lel.pop_front(); --size; ++ aelSize; } if (aelSize) { borderFound = false; for (elIt = ael.begin(); elIt != ael.end();) { if (elIt->P2.y <= currY) { // edge has gone out of active edge list elIt = ael.erase(elIt); if (! --aelSize) return; continue; } else { if (elIt->P1.y >= currY) { if (!borderFound) { left = right = elIt->P1.x; borderFound = true; } else { left = std::min(left, elIt->P1.x); right = std::max(right, elIt->P1.x); } } else { // compute intersection diff = elIt->P2.y - elIt->P1.y; if (diff > epsilon) { inter = elIt->P1.x + (elIt->P2.x - elIt->P1.x) * (currY - elIt->P1.y) / diff; } else { inter = elIt->P2.x; } if (!borderFound) { left = right = inter; borderFound = true; } else { left = std::min(left, inter); right = std::max(right, inter); } } if (elIt->P2.y <= currY + quadHeight) { if (!borderFound) { left = right = elIt->P2.x; borderFound = true; } else { left = std::min(left, elIt->P2.x); right = std::max(right, elIt->P2.x); } } else { // compute intersection diff = elIt->P2.y - elIt->P1.y; if (diff > epsilon) { inter = elIt->P1.x + (elIt->P2.x - elIt->P1.x) * (currY + quadHeight - elIt->P1.y) / diff; } else { inter = elIt->P2.x; } if (!borderFound) { left = right = inter; borderFound = true; } else { left = std::min(left, inter); right = std::max(right, inter); } } } ++ elIt; } dest.push_back(std::make_pair(left, right)); } currY += quadHeight; } while (size || aelSize); }

void NL3D::CQuadEffect::processPoly (  const TPoint2DVect &  poly, float  quadWidth, float  quadHeight, TPoint2DVect &  dest )  [static]

Tesselate the given clipped polygon , by using the given quad dimensions The coordinates of the poly are given in screen coordinate. Parameters: poly  a polygon that describe the area where datas are taken from. quadWidth  width of the quad quadHeight  height of the quad dest  a vector that will contains the pos of all the quads that cover the poly Definition at line 234 of file quad_effect.cpp. References makeRasters(), sint, and TRasters. { static TRasters rDest; float currY; makeRasters(poly, quadWidth, quadHeight, rDest, currY); if (dest.size()) { TRasters::const_iterator it, endIt = rDest.end(); for (it = rDest.begin(); it != endIt; ++it) { const sint nbQuad = (sint) ceilf( (it->second - it->first) / quadWidth); float currX = it->first; for (sint k = 0; k < nbQuad; ++k) { dest.push_back(NLMISC::CVector2f(currX, currY)); currX += quadWidth; } currY += quadHeight; } } }

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

• quad_effect.h
• quad_effect.cpp

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