import numpy as np
import imageio.v3 as iio

# --- Parameters ---
WIDTH, HEIGHT = 1024, 1024
CENTER_X, CENTER_Y = WIDTH // 2, HEIGHT // 2
RADIUS = 150
BACKGROUND_COLOR = 0.0  # Pure black
# This is the key change: A "super-white" HDR value for the circle.
# A value of 5.0 simulates a very bright light source.
CIRCLE_BRIGHTNESS = 5.0
OUTPUT_FILENAME = "halation_test_hdr.tiff"

# --- Generate the image ---
# Create coordinate grids
y, x = np.mgrid[:HEIGHT, :WIDTH]

# Calculate distance from the center
distance = np.sqrt((x - CENTER_X)**2 + (y - CENTER_Y)**2)

# Create a circular mask
mask = distance <= RADIUS

# Create a 3-channel float image
# Use float32, as it's a standard for HDR images
image_hdr = np.full((HEIGHT, WIDTH, 3), BACKGROUND_COLOR, dtype=np.float32)

# Set the circle area to the super-white value
image_hdr[mask] = [CIRCLE_BRIGHTNESS, CIRCLE_BRIGHTNESS, CIRCLE_BRIGHTNESS]

# --- Save the image ---
# Save as a 32-bit float TIFF to preserve the HDR values
iio.imwrite(OUTPUT_FILENAME, image_hdr)

print(f"✅ Saved HDR test image to '{OUTPUT_FILENAME}'")
print(f"   Use this file as the input for your film simulation script.")