Color Collision Detection

Color collision detection is a custom function in PIGO8 that allows you to check if a pixel at specific coordinates matches a specified color. This is useful for color-based collision detection in games.

Overview

The ColorCollision function checks if the pixel at the given coordinates (x, y) matches a specific color from the PICO-8 palette. This can be used for various collision detection scenarios, such as checking if a character is touching a specific terrain type or obstacle represented by a particular color.

Function Signature

func ColorCollision[X Number, Y Number](x X, y Y, color int) bool

Parameters

x: The x-coordinate to check (0-127), can be any numeric type
y: The y-coordinate to check (0-127), can be any numeric type
color: The PICO-8 color index to check against (0-15)

Return Value

bool: Returns true if the pixel at (x, y) matches the specified color, false otherwise

Example Usage

package main

import p8 "github.com/drpaneas/pigo8"

type Game struct {
    playerX, playerY float64
    wallColor        int
}

func (g *Game) Init() {
    g.playerX = 64
    g.playerY = 64
    g.wallColor = 3 // Assuming color 3 represents walls
}

func (g *Game) Update() {
    // Store original position
    origX, origY := g.playerX, g.playerY
    
    // Move player based on input
    if p8.Btn(p8.ButtonRight) {
        g.playerX++
    }
    
    // Check if the player is touching a wall (color 3)
    if p8.ColorCollision(g.playerX, g.playerY, g.wallColor) {
        // Player is touching a wall, revert to previous position
        g.playerX, g.playerY = origX, origY
        
        // Play collision sound
        p8.Music(0)
    }
}

How It Works

The color collision detection function:

Validates that the coordinates are within the screen bounds (0-127)
Validates that the color index is valid (0-15)
Gets the color of the pixel at the specified coordinates using Pget
Compares the pixel color with the specified color
Returns true if they match, false otherwise

Use Cases

Color collision detection is useful for:

Terrain-based collision (e.g., detecting water, lava, or solid ground)
Color-coded obstacle detection
Pixel-perfect collision in games with detailed environments
Detecting when a character enters specific areas marked by color

Performance Considerations

For optimal performance:

Use this function sparingly, as checking individual pixels can be CPU-intensive
Consider checking only key points of your game objects (e.g., corners or center) rather than every pixel
For larger objects, combine with bounding box checks first

Complete Example

You can find a complete example of color collision detection in the examples/colorCollision directory.

PIGO8 Documentation