Map Collision

Check if a rectangular area overlaps with flagged map tiles.

MapCollision Function

p8.MapCollision(x, y, flag, width, height) bool

Returns true if any tile under the area has the specified flag set.

Parameters

Basic Usage

// Check 8×8 area at player position
if p8.MapCollision(g.playerX, g.playerY, 0) {
    // Hit a tile with flag 0 (solid)
}

Custom Hitbox

// Player is 6×12 pixels
playerWidth := 6
playerHeight := 12
if p8.MapCollision(g.x, g.y, 0, playerWidth, playerHeight) {
    // Collision
}

Platformer Movement

func (g *game) Update() {
    // Horizontal movement
    newX := g.x + g.velocityX
    if !p8.MapCollision(newX, g.y, 0, 8, 8) {
        g.x = newX
    } else {
        g.velocityX = 0
    }
    
    // Vertical movement
    newY := g.y + g.velocityY
    if !p8.MapCollision(g.x, newY, 0, 8, 8) {
        g.y = newY
    } else {
        if g.velocityY > 0 {
            g.onGround = true
        }
        g.velocityY = 0
    }
}

Different Collision Types

Use different flags for different behaviors:

const (
    FlagSolid    = 0  // Can't pass through
    FlagPlatform = 1  // Pass through from below
    FlagHazard   = 2  // Damages player
    FlagWater    = 3  // Slows movement
)

func (g *game) Update() {
    // Check solid collision
    if p8.MapCollision(g.x, g.y+1, FlagSolid) {
        g.onGround = true
    }
    
    // Check hazards
    if p8.MapCollision(g.x, g.y, FlagHazard) {
        g.takeDamage()
    }
    
    // Check water (for movement speed)
    g.inWater = p8.MapCollision(g.x, g.y, FlagWater)
}