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tracebox.go
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tracebox.go
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// Copyright 2021 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package engine
import (
"github.com/divVerent/aaaaxy/internal/level"
"github.com/divVerent/aaaaxy/internal/log"
m "github.com/divVerent/aaaaxy/internal/math"
)
func (l *normalizedLine) traceBoxTiles(w *World, o TraceOptions, enlarge m.Delta, result *TraceResult) {
if o.PathOut != nil {
*o.PathOut = append(*o.PathOut, l.Origin.Div(level.TileSize))
}
// Find the corner in direction of the trace.
var adjustment m.Delta
if l.XDir > 0 {
adjustment.DX = enlarge.DX
}
if l.YDir > 0 {
adjustment.DY = enlarge.DY
}
// Trace that corner path against the tilemap.
// TODO: do this more efficiently than copying the line. We maybe can
// even reuse the same adjustment for entity tracing? Or just edit the
// l object and reset when done?
ll := *l
ll.Origin = ll.Origin.Add(adjustment)
ll.Target = ll.Target.Add(adjustment)
ll.walkTiles(func(prevTile, nextTile m.Pos, delta m.Delta, prevPixelAdj, nextPixelAdj m.Pos) error {
// First, unadjust.
prevPixel := prevPixelAdj.Sub(adjustment)
nextPixel := nextPixelAdj.Sub(adjustment)
// Check the newly hit tiles.
if nextPixel.X != prevPixel.X {
// X move.
// Check all newly hit tiles in Y range.
// TODO: One of these divisions is redundant. Worth optimizing?
top := m.Div(nextPixel.Y, level.TileSize)
bottom := m.Div(nextPixel.Y+enlarge.DY, level.TileSize)
for y := top; y <= bottom; y++ {
tilePos := m.Pos{X: nextTile.X, Y: y}
var tile *level.Tile
if o.LoadTiles {
tile = w.LoadTile(tilePos.Sub(delta), tilePos, delta)
} else {
tile = w.Tile(tilePos)
}
if tile == nil {
result.EndPos = prevPixel
result.HitDelta = delta
// result.HitFogOfWar = true
return traceDoneErr
}
if o.Contents&tile.Contents != 0 {
result.EndPos = prevPixel
result.HitDelta = delta
// result.HitTilePos = nextTile
// result.HitTile = tile
return traceDoneErr
}
}
} else {
// Y move.
// Check all newly hit tiles in X range.
// TODO: One of these divisions is redundant. Worth optimizing?
left := m.Div(nextPixel.X, level.TileSize)
right := m.Div(nextPixel.X+enlarge.DX, level.TileSize)
for x := left; x <= right; x++ {
tilePos := m.Pos{X: x, Y: nextTile.Y}
var tile *level.Tile
if o.LoadTiles {
tile = w.LoadTile(tilePos.Sub(delta), tilePos, delta)
} else {
tile = w.Tile(tilePos)
}
if tile == nil {
result.EndPos = prevPixel
result.HitDelta = delta
// result.HitFogOfWar = true
return traceDoneErr
}
if o.Contents&tile.Contents != 0 {
result.EndPos = prevPixel
result.HitDelta = delta
// result.HitTilePos = nextTile
// result.HitTile = tile
return traceDoneErr
}
}
}
return nil
})
}
func traceBox(w *World, from m.Rect, to m.Pos, o TraceOptions) TraceResult {
if o.Contents == level.NoContents {
log.Fatalf("do not know what to stop at - need to specify Contents in every trace")
}
result := TraceResult{
EndPos: to,
// HitTile: nil,
// HitEntities: nil,
// HitFogOfWar: false,
}
if from.Origin == to {
// Empty trace? Nothign we can hit.
return result
}
l := normalizeLine(from.Origin, to)
// As from != to, we know NumSteps > 0.
enlarge := from.Size.Sub(m.Delta{DX: 1, DY: 1})
maxBorder := 0
if o.ForEnt != nil {
maxBorder = o.ForEnt.BorderPixels
}
if !o.NoTiles {
l.traceBoxTiles(w, o, enlarge, &result)
}
if !o.NoEntities {
l.traceEntities(w, o, enlarge, maxBorder, &result)
}
return result
}