Collision

NOTE: This document will be deprecated in the near future. Some items may be outdated/incorrect

Collision is driven by a 2D tile map overlaid on the 3D world. Each area/scene has a .jmap file in assets/maps/ that defines the tile grid (see JMAPS.md for the format.)

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How It Works

The world is divided into a grid of equally-sized tiles. CharacterController tracks the character’s world-space position and converts it to tile coordinates:

tileX = (worldX + worldOffsetX) / tileSize
tileZ = (worldZ + worldOffsetZ) / tileSize

Before each movement, the controller checks whether the destination tile is walkable. It tries three combinations to allow wall-sliding:

1. Full movement (X + Z)
2. X only (slide along a Z wall)
3. Z only (slide along an X wall)

The character has a bounding box (characterSize). All four corners are checked, not just the center, so the character can’t clip through narrow walls.

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Tile Types

Defined in source/controllers/CharacterController.h:

Value	Enum	jmap key	Description
0	NO_COLLISION	w	Walkable area
1	COLLISION	c	Solid wall, blocks movement
2	SAVE	s	Save interaction zone
3	PREV_SCENE	p	Transition to previous scene
4	NEXT_SCENE	e	Transition to next scene
100	CHARACTER_Akihiko	c_a	NPC trigger zone

Tiles outside the map bounds default to NO_COLLISION.

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World Offset & Tile Size

worldOffsetX and worldOffsetZ shift the tile grid to align with the 3D geometry. tileSize sets how many world units one tile covers. These are defined per-view and must match the scale of the environment model. Use the world offset calculator tool in /tools if you need to recalculate them.

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Checking Tile Type in a View

TileType tile = playerCtrl->isTileAt();

if (tile == TileType::NEXT_SCENE) {
    // transition to next area
} else if (tile == TileType::CHARACTER_Akihiko) {
    // show NPC prompt
}

isTileAt() returns the tile type at the character’s current center position. This is called every frame in the view’s Update().