Overview

An Atlas, like a Texture, represents raw image data in GPU memory. However, an Atlas also has an associated two-dimensional "partition size" which must evenly partition the underlying texture. Instead of blitting the entire texture, specific sub-regions can be drawn by referencing them numerically. The indexes are assigned left-to-right and top-to-bottom:

Example sub-region layouts

+---+---+---+      +---+---+
|   |   |   |      |   |   |
| 0 | 1 | 2 |      | 0 | 1 |
|   |   |   |      |   |   |
+-----------+      +-------+     +---+---+---+---+---+---+
|   |   |   |      |   |   |     |   |   |   |   |   |   |
| 3 | 4 | 5 |      | 2 | 3 |     | 0 | 1 | 2 | 3 | 4 | 5 |
|   |   |   |      |   |   |     |   |   |   |   |   |   |
+---+---+---+      +-------+     +---+---+---+---+---+---+
                   |   |   |
                   | 4 | 5 |
                   |   |   |
                   +---+---+

Imports

json, marshal, os, strutils, tables, sdl2, exceptions, packs, textures, utils

Types

AtlasInfo = object filename*: string ## filename used to load the Atlas width*: int ## the width of the Atlas partition height*: int ## the height of the Atlas partition name*: string ## name of the Atlas in an AtlasManager description*: string ## description of the Atlas authors*: seq[string] ## authors of the Atlas: Meta-data describing an Atlas
Atlas = ref object info*: AtlasInfo ## meta-data describing the Atlas width*: int ## Atlas width in sub-regions height*: int ## Atlas height in sub-regions texture*: Texture ## Texture underlying the Atlas: Used for rendering sub-regions of a Texture
AtlasManager = ref object textures: TextureManager ## textures backing managed Atlases registry: Table[string, Atlas] ## loaded Atlases by name: Used for loading and managing Atlases

Procs

proc newAtlasManager(window: WindowPtr; display: RendererPtr): AtlasManager {. raises: [], tags: [].}

proc load(am: AtlasManager; name, filename: string; width, height: int; description: string = nil; authors: seq[string] = nil): Atlas {. raises: [KeyError, NoSuchResourceError, ValueError, InvalidResourceError], tags: [ReadDirEffect].}

Load an image resource from disk partitioned into sub-regions of width and height. Once loaded sub-regions may be rendered by index. The Atlas can be retrieved from the AtlasManager using the provided name.

proc loadPack(am: AtlasManager; filename: string) {.raises: [ValueError, IOError, Exception, JsonParsingError, IndexError, KeyError, NoSuchResourceError, InvalidResourceError], tags: [ReadIOEffect, RootEffect, ReadDirEffect].}

Load a resource-pack of Altases. Assets inside of an Atlas resource-pack should be unmarshalable by the AtlasAsset type.

Example AtlasAsset JSON

"example_atlas_asset": {
  "filename": "atlases/example_atlas.png",
  "width": 32, "height": 32
}

proc get(am: AtlasManager; name: string): Atlas {. raises: [NoSuchResourceError, KeyError], tags: [].}

Get a loaded Atlas by name

proc render(display: RendererPtr; atlas: Atlas; rx, ry, dx, dy: int) {.raises: [], tags: [].}

Render the sub-region rx, ry of atlas to the destination dx, dy of display

proc render(display: RendererPtr; atlas: Atlas; n, dx, dy: int) {. raises: [DivByZeroError], tags: [].}

Render the indexed sub-region n of atlas to the destination dx, dy of display

Module atlases

Overview

Imports

Types

Procs