0ad/source/simulation2/helpers/Rasterize.cpp
2016-11-23 14:09:58 +00:00

126 lines
4.9 KiB
C++

/* Copyright (C) 2015 Wildfire Games.
* This file is part of 0 A.D.
*
* 0 A.D. is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* 0 A.D. is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
*/
#include "precompiled.h"
#include "Rasterize.h"
#include "simulation2/helpers/Geometry.h"
void SimRasterize::RasterizeRectWithClearance(Spans& spans,
const ICmpObstructionManager::ObstructionSquare& shape,
entity_pos_t clearance, entity_pos_t cellSize)
{
// A long-standing issue with the pathfinding has been that the long-range one
// uses a AA navcell grid, while the short-range uses an accurate vector representation.
// This means we could get paths accepted by one but not both pathfinders.
// Since the new pathfinder, the short-range pathfinder's representation was usually
// encompassing the rasterisation of the long-range one for a building.
// This means that we could never get quite as close as the long-range pathfinder wanted.
// This could mean units tried going through impassable paths.
// To fix this, we need to make sure that the short-range pathfinder is always mostly
// included in the rasterisation. The easiest way is to rasterise more, thus this variable
// Since this is a very complicated subject, check out logs on 31/10/2015 for more detailled info.
// or ask wraitii about it.
// If the short-range pathfinder is sufficiently changed, this could become unnecessary and thus removed.
// A side effect is that the basic clearance has been set to 0.8, so removing this constant should be done
// in parallel with setting clearance back to 1 for the default passability class (though this isn't strictly necessary).
// Also: the code detecting foundation obstruction in CcmpObstructionManager had to be changed similarly.
entity_pos_t rasterClearance = clearance + Pathfinding::CLEARANCE_EXTENSION_RADIUS;
// Get the bounds of cells that might possibly be within the shape
// (We'll then test each of those cells more precisely)
CFixedVector2D shapeHalfSize(CFixedVector2D(shape.hw, shape.hh));
CFixedVector2D halfSize(shape.hw + rasterClearance, shape.hh + rasterClearance);
CFixedVector2D halfBound = Geometry::GetHalfBoundingBox(shape.u, shape.v, halfSize);
i16 i0 = ((shape.x - halfBound.X) / cellSize).ToInt_RoundToNegInfinity();
i16 j0 = ((shape.z - halfBound.Y) / cellSize).ToInt_RoundToNegInfinity();
i16 i1 = ((shape.x + halfBound.X) / cellSize).ToInt_RoundToInfinity();
i16 j1 = ((shape.z + halfBound.Y) / cellSize).ToInt_RoundToInfinity();
if (j1 <= j0)
return; // empty bounds - this shouldn't happen
rasterClearance = rasterClearance.Multiply(rasterClearance);
spans.reserve(j1 - j0);
for (i16 j = j0; j < j1; ++j)
{
// Find the min/max range of cells that are strictly inside the square+rasterClearance.
// (Since the square+rasterClearance is a convex shape, we can just test each
// corner of each cell is inside the shape.)
// When looping on i, if the previous cell was inside, no need to check again the left corners.
// and we can stop the loop when exiting the shape.
// Futhermore if one of the right corners of a cell is outside, no need to check the following cell
i16 spanI0 = std::numeric_limits<i16>::max();
i16 spanI1 = std::numeric_limits<i16>::min();
bool previousInside = false;
bool skipNextCell = false;
for (i16 i = i0; i < i1; ++i)
{
if (skipNextCell)
{
skipNextCell = false;
continue;
}
if (Geometry::DistanceToSquareSquared(CFixedVector2D(cellSize*(i+1)-shape.x, cellSize*j-shape.z),
shape.u, shape.v, shapeHalfSize, true) > rasterClearance)
{
if (previousInside)
break;
skipNextCell = true;
continue;
}
if (Geometry::DistanceToSquareSquared(CFixedVector2D(cellSize*(i+1)-shape.x, cellSize*(j+1)-shape.z),
shape.u, shape.v, shapeHalfSize, true) > rasterClearance)
{
if (previousInside)
break;
skipNextCell = true;
continue;
}
if (!previousInside)
{
if (Geometry::DistanceToSquareSquared(CFixedVector2D(cellSize*i-shape.x, cellSize*j-shape.z),
shape.u, shape.v, shapeHalfSize, true) > rasterClearance)
continue;
if (Geometry::DistanceToSquareSquared(CFixedVector2D(cellSize*i-shape.x, cellSize*(j+1)-shape.z),
shape.u, shape.v, shapeHalfSize, true) > rasterClearance)
continue;
previousInside = true;
spanI0 = i;
}
spanI1 = i+1;
}
// Add non-empty spans onto the list
if (spanI0 < spanI1)
{
Span span = { spanI0, spanI1, j };
spans.push_back(span);
}
}
}