50 lines
1.6 KiB
Markdown
50 lines
1.6 KiB
Markdown
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# Grid Data Structure Ideas
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Ideas for managing level pixel grids.
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## Chunks
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Divide the grid into Chunks of an arbitrary size. The canvas metadata would
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specify the chunk size (e.g. 1000x1000 pixels) so it's able to vary by the
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drawing itself.
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A `ChunkManager` structure would wrap around the chunks and give each one a
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coordinate value. To convert an absolute pixel value into a chunk coordinate
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you multiply it by the chunk size.
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So a pixel coord of `123456` in a map with 1000x1000 chunk sizes would be
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`(123456) / 1000 = 123.456 = 123` (rounded down). This would give you a chunk
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index and then that chunk is responsible for knowing where the exact pixel is.
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## Chunk Types
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Each chunk could organize its pixels into two types of structures depending
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on the density of the chunk:
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1. A hash map for sparse chunks.
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2. A 2D array of fixed size for dense chunks.
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So if a chunk is <70% filled it would use a hash map and when it gets heavier
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than that, switch to a 2D array.
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Something like,
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```go
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type Chunk struct {
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Type int `json:"type"` // map vs. 2D array
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Map map[Point]int // map of (X,Y) points to Palette entry
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Grid [][]int // 2D array of Palette entries
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}
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```
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## External Chunks
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For normal single-player maps that aren't infinite in size, all the chunks
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are stored in the singular level file. Larger maps can start saving their
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chunks to disk in external files.
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Some internal threshhold can be used to decide when to start saving chunks
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as external files. If the chunk size is 1000x1000 pixels it could start saving
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external files after (say) 9 different chunks are allocated for the first time,
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or some time/space tradeoff like that.
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