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Pull out chunk based atlas into new file

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This commit is contained in:
Marc Di Luzio 2020-07-10 16:54:43 +01:00
parent 655e00b41f
commit a0be8a463c
4 changed files with 281 additions and 275 deletions
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260
pkg/atlas/atlas.go
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@ -1,13 +1,8 @@
package atlas
import (
"log"
"math/rand"
"github.com/mdiluz/rove/pkg/maths"
"github.com/mdiluz/rove/pkg/objects"
"github.com/mdiluz/rove/pkg/vector"
"github.com/ojrac/opensimplex-go"
)
// Tile describes the type of terrain
@ -38,258 +33,3 @@ type Atlas interface {
// QueryPosition queries a position on the atlas
QueryPosition(v vector.Vector) (byte, objects.Object)
}
// chunk represents a fixed square grid of tiles
type chunk struct {
// Tiles represents the tiles within the chunk
Tiles []byte `json:"tiles"`
// Objects represents the objects within the chunk
// only one possible object per tile for now
Objects map[int]objects.Object `json:"objects"`
}
// ChunkBasedAtlas represents a grid of Chunks
type ChunkBasedAtlas struct {
// Chunks represents all chunks in the world
// This is intentionally not a 2D array so it can be expanded in all directions
Chunks []chunk `json:"chunks"`
// LowerBound is the origin of the bottom left corner of the current chunks in world space (current chunks cover >= this value)
LowerBound vector.Vector `json:"lowerBound"`
// UpperBound is the top left corner of the current chunks (curent chunks cover < this value)
UpperBound vector.Vector `json:"upperBound"`
// ChunkSize is the x/y dimensions of each square chunk
ChunkSize int `json:"chunksize"`
// terrainNoise describes the noise function for the terrain
terrainNoise opensimplex.Noise
// terrainNoise describes the noise function for the terrain
objectNoise opensimplex.Noise
}
const (
noiseSeed = 1024
terrainNoiseScale = 6
objectNoiseScale = 3
)
// NewAtlas creates a new empty atlas
func NewAtlas(chunkSize int) Atlas {
// Start up with one chunk
a := ChunkBasedAtlas{
ChunkSize: chunkSize,
Chunks: make([]chunk, 1),
LowerBound: vector.Vector{X: 0, Y: 0},
UpperBound: vector.Vector{X: chunkSize, Y: chunkSize},
terrainNoise: opensimplex.New(noiseSeed),
objectNoise: opensimplex.New(noiseSeed),
}
// Initialise the first chunk
a.populate(0)
return &a
}
// SetTile sets an individual tile's kind
func (a *ChunkBasedAtlas) SetTile(v vector.Vector, tile Tile) {
c := a.worldSpaceToChunkWithGrow(v)
local := a.worldSpaceToChunkLocal(v)
a.setTile(c, local, byte(tile))
}
// SetObject sets the object on a tile
func (a *ChunkBasedAtlas) SetObject(v vector.Vector, obj objects.Object) {
c := a.worldSpaceToChunkWithGrow(v)
local := a.worldSpaceToChunkLocal(v)
a.setObject(c, local, obj)
}
// QueryPosition will return information for a specific position
func (a *ChunkBasedAtlas) QueryPosition(v vector.Vector) (byte, objects.Object) {
c := a.worldSpaceToChunkWithGrow(v)
local := a.worldSpaceToChunkLocal(v)
a.populate(c)
chunk := a.Chunks[c]
i := a.chunkTileIndex(local)
return chunk.Tiles[i], chunk.Objects[i]
}
// chunkTileID returns the tile index within a chunk
func (a *ChunkBasedAtlas) chunkTileIndex(local vector.Vector) int {
return local.X + local.Y*a.ChunkSize
}
// populate will fill a chunk with data
func (a *ChunkBasedAtlas) populate(chunk int) {
c := a.Chunks[chunk]
if c.Tiles != nil {
return
}
c.Tiles = make([]byte, a.ChunkSize*a.ChunkSize)
c.Objects = make(map[int]objects.Object)
origin := a.chunkOriginInWorldSpace(chunk)
for i := 0; i < a.ChunkSize; i++ {
for j := 0; j < a.ChunkSize; j++ {
// Get the terrain noise value for this location
t := a.terrainNoise.Eval2(float64(origin.X+i)/terrainNoiseScale, float64(origin.Y+j)/terrainNoiseScale)
var tile Tile
switch {
case t > 0.5:
tile = TileGravel
case t > 0.05:
tile = TileSand
default:
tile = TileRock
}
c.Tiles[j*a.ChunkSize+i] = byte(tile)
// Get the object noise value for this location
o := a.objectNoise.Eval2(float64(origin.X+i)/objectNoiseScale, float64(origin.Y+j)/objectNoiseScale)
var obj = objects.None
switch {
case o > 0.6:
obj = objects.LargeRock
case o > 0.5:
obj = objects.SmallRock
}
if obj != objects.None {
c.Objects[j*a.ChunkSize+i] = objects.Object{Type: obj}
}
}
}
// Set up any objects
for i := 0; i < len(c.Tiles); i++ {
if rand.Intn(16) == 0 {
c.Objects[i] = objects.Object{Type: objects.LargeRock}
} else if rand.Intn(32) == 0 {
c.Objects[i] = objects.Object{Type: objects.SmallRock}
}
}
a.Chunks[chunk] = c
}
// setTile sets a tile in a specific chunk
func (a *ChunkBasedAtlas) setTile(chunk int, local vector.Vector, tile byte) {
a.populate(chunk)
c := a.Chunks[chunk]
c.Tiles[a.chunkTileIndex(local)] = tile
a.Chunks[chunk] = c
}
// setObject sets an object in a specific chunk
func (a *ChunkBasedAtlas) setObject(chunk int, local vector.Vector, object objects.Object) {
a.populate(chunk)
c := a.Chunks[chunk]
i := a.chunkTileIndex(local)
if object.Type != objects.None {
c.Objects[i] = object
} else {
delete(c.Objects, i)
}
a.Chunks[chunk] = c
}
// worldSpaceToChunkLocal gets a chunk local coordinate for a tile
func (a *ChunkBasedAtlas) worldSpaceToChunkLocal(v vector.Vector) vector.Vector {
return vector.Vector{X: maths.Pmod(v.X, a.ChunkSize), Y: maths.Pmod(v.Y, a.ChunkSize)}
}
// worldSpaceToChunkID gets the current chunk ID for a position in the world
func (a *ChunkBasedAtlas) worldSpaceToChunkIndex(v vector.Vector) int {
// Shift the vector by our current min
v = v.Added(a.LowerBound.Negated())
// Divide by the current size and floor, to get chunk-scaled vector from the lower bound
v = v.DividedFloor(a.ChunkSize)
// Calculate the width
width := a.UpperBound.X - a.LowerBound.X
widthInChunks := width / a.ChunkSize
// Along the corridor and up the stairs
return (v.Y * widthInChunks) + v.X
}
// chunkOriginInWorldSpace returns the origin of the chunk in world space
func (a *ChunkBasedAtlas) chunkOriginInWorldSpace(chunk int) vector.Vector {
// Calculate the width
width := a.UpperBound.X - a.LowerBound.X
widthInChunks := width / a.ChunkSize
// Reverse the along the corridor and up the stairs
v := vector.Vector{
X: chunk % widthInChunks,
Y: chunk / widthInChunks,
}
// Multiply up to world scale
v = v.Multiplied(a.ChunkSize)
// Shift by the lower bound
return v.Added(a.LowerBound)
}
// getNewBounds gets new lower and upper bounds for the world space given a vector
func (a *ChunkBasedAtlas) getNewBounds(v vector.Vector) (lower vector.Vector, upper vector.Vector) {
lower = vector.Min(v, a.LowerBound)
upper = vector.Max(v.Added(vector.Vector{X: 1, Y: 1}), a.UpperBound)
lower = vector.Vector{
X: maths.RoundDown(lower.X, a.ChunkSize),
Y: maths.RoundDown(lower.Y, a.ChunkSize),
}
upper = vector.Vector{
X: maths.RoundUp(upper.X, a.ChunkSize),
Y: maths.RoundUp(upper.Y, a.ChunkSize),
}
return
}
// worldSpaceToTrunkWithGrow will expand the current atlas for a given world space position if needed
func (a *ChunkBasedAtlas) worldSpaceToChunkWithGrow(v vector.Vector) int {
// If we're within bounds, just return the current chunk
if v.X >= a.LowerBound.X && v.Y >= a.LowerBound.Y && v.X < a.UpperBound.X && v.Y < a.UpperBound.Y {
return a.worldSpaceToChunkIndex(v)
}
// Calculate the new bounds
lower, upper := a.getNewBounds(v)
size := upper.Added(lower.Negated())
size = size.Divided(a.ChunkSize)
// Create the new empty atlas
newAtlas := ChunkBasedAtlas{
ChunkSize: a.ChunkSize,
LowerBound: lower,
UpperBound: upper,
Chunks: make([]chunk, size.X*size.Y),
terrainNoise: a.terrainNoise,
objectNoise: a.objectNoise,
}
// Log that we're resizing
log.Printf("Re-allocating world, old: %+v,%+v new: %+v,%+v\n", a.LowerBound, a.UpperBound, newAtlas.LowerBound, newAtlas.UpperBound)
// Copy all old chunks into the new atlas
for chunk, chunkData := range a.Chunks {
// Calculate the chunk ID in the new atlas
origin := a.chunkOriginInWorldSpace(chunk)
newChunk := newAtlas.worldSpaceToChunkIndex(origin)
// Copy over the old chunk to the new atlas
newAtlas.Chunks[newChunk] = chunkData
}
// Overwrite the old atlas with this one
*a = newAtlas
return a.worldSpaceToChunkIndex(v)
}