FOV

Field of view algorithm enumeration.

Overview

FOV is an IntEnum that specifies which algorithm to use when computing field of view on a Grid. Different algorithms offer trade-offs between performance, accuracy, and visual characteristics. The algorithms are provided by libtcod.

Quick Reference

# Set FOV algorithm on grid
grid.fov = mcrfpy.FOV.FOV_SHADOW

# Compute FOV from position
grid.compute_fov(player.x, player.y, radius=8)

# Check visibility
if grid.is_in_fov(target_x, target_y):
    print("Target is visible!")

# Available algorithms
mcrfpy.FOV.FOV_BASIC
mcrfpy.FOV.FOV_DIAMOND
mcrfpy.FOV.FOV_SHADOW
mcrfpy.FOV.FOV_PERMISSIVE_0  # through FOV_PERMISSIVE_8

Constructor

FOV is an IntEnum and its values are accessed as class attributes.

algorithm = mcrfpy.FOV.FOV_SHADOW

Values

Value	Description
`FOV_BASIC`	Basic raycasting algorithm. Fast but can miss corners.
`FOV_DIAMOND`	Diamond-shaped FOV. Symmetric and predictable.
`FOV_SHADOW`	Shadow casting algorithm. Most commonly used, good balance.
`FOV_PERMISSIVE_0`	Permissive FOV, strictest. Narrowest field of view.
`FOV_PERMISSIVE_1`	Permissive FOV level 1
`FOV_PERMISSIVE_2`	Permissive FOV level 2
`FOV_PERMISSIVE_3`	Permissive FOV level 3
`FOV_PERMISSIVE_4`	Permissive FOV level 4 (middle)
`FOV_PERMISSIVE_5`	Permissive FOV level 5
`FOV_PERMISSIVE_6`	Permissive FOV level 6
`FOV_PERMISSIVE_7`	Permissive FOV level 7
`FOV_PERMISSIVE_8`	Permissive FOV, most permissive. Widest field of view.

Algorithm Comparison

FOV_BASIC

Simple raycasting from the viewer to each cell. Fast computation but can produce asymmetric results where the player can see a cell but an enemy at that cell cannot see the player.

FOV_DIAMOND

Creates a diamond-shaped visible area. Produces symmetric results and is easy to understand, but may not look as natural as shadow casting.

FOV_SHADOW (Recommended)

The most popular algorithm for roguelikes. Casts shadows from obstacles to determine visibility. Produces natural-looking results with good performance. This is the default choice for most games.

FOV_PERMISSIVE_0 through FOV_PERMISSIVE_8

A family of algorithms that vary in how “permissive” they are about visibility around corners. Lower numbers (0-3) are stricter and show less around corners. Higher numbers (5-8) are more permissive and reveal more. Level 4 is the middle ground.

Usage Patterns

Basic FOV Setup

# Create grid and set algorithm
grid = mcrfpy.Grid(grid_size=(80, 45), texture=texture)
grid.fov = mcrfpy.FOV.FOV_SHADOW
grid.fov_radius = 10

# Compute FOV from player position
grid.compute_fov(player.x, player.y)

# Use in visibility checks
for enemy in enemies:
    if grid.is_in_fov(enemy.x, enemy.y):
        enemy.visible = True

FOV with Color Layer

fog = grid.add_layer('color', z_index=10)
fog.fill(mcrfpy.Color(0, 0, 0, 255))  # Start dark

def update_visibility():
    grid.compute_fov(player.x, player.y, radius=8)
    fog.draw_fov(grid)  # Reveal visible cells

Algorithm Selection

# For classic roguelike feel
grid.fov = mcrfpy.FOV.FOV_SHADOW

# For tactical games where seeing around corners matters
grid.fov = mcrfpy.FOV.FOV_PERMISSIVE_6

# For symmetric stealth games
grid.fov = mcrfpy.FOV.FOV_DIAMOND

# For fast computation in large maps
grid.fov = mcrfpy.FOV.FOV_BASIC

Dynamic Algorithm Switching

# Different FOV for different game modes
def set_stealth_mode():
    grid.fov = mcrfpy.FOV.FOV_PERMISSIVE_2  # Limited vision
    grid.fov_radius = 5

def set_alert_mode():
    grid.fov = mcrfpy.FOV.FOV_SHADOW
    grid.fov_radius = 12

FOV