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#!/usr/bin/env python3
import numpy as np
from math import sin, cos, atan2, hypot
from basisu_py.codec import Encoder, EncoderBackend
from basisu_py.constants import BasisTexFormat, BasisQuality, BasisEffort, BasisFlags
# --------------------------------------------------------------
# Procedural HDR swirl pattern (float32 RGBA)
# --------------------------------------------------------------
def make_hdr_swirl_image(w=256, h=256):
arr = np.zeros((h, w, 4), dtype=np.float32)
cx = w / 2.0
cy = h / 2.0
for y in range(h):
for x in range(w):
dx = x - cx
dy = y - cy
dist = hypot(dx, dy)
angle = atan2(dy, dx)
r = (sin(dist * 0.15) * 0.5 + 0.5)
g = (sin(angle * 3.0) * 0.5 + 0.5)
b = (cos(dist * 0.10 + angle * 2.0) * 0.5 + 0.5)
arr[y, x] = (r, g, b, 1.0) # full alpha
return arr
# --------------------------------------------------------------
# Test encode using a given backend
# --------------------------------------------------------------
def compress_hdr_swirl(backend, outfile):
print(f"\n========== Testing HDR {backend} backend ==========")
hdr = make_hdr_swirl_image(256, 256)
print("Generated HDR swirl image:", hdr.shape, hdr.dtype)
enc = Encoder(backend=backend)
blob = enc.compress(
hdr,
format=-1, # auto-select HDR (UASTC_HDR_4x4)
quality=BasisQuality.MAX,
effort=BasisEffort.DEFAULT,
flags=BasisFlags.KTX2_OUTPUT | BasisFlags.SRGB
)
print(f"Compressed blob size: {len(blob)} bytes")
with open(outfile, "wb") as f:
f.write(blob)
print(f"Wrote: {outfile}")
print("==============================================")
# --------------------------------------------------------------
# Main
# --------------------------------------------------------------
if __name__ == "__main__":
# Native backend
try:
compress_hdr_swirl(EncoderBackend.NATIVE, "hdr_swirl_native.ktx2")
except Exception as e:
print("Native HDR backend ERROR:", e)
# WASM backend
try:
compress_hdr_swirl(EncoderBackend.WASM, "hdr_swirl_wasm.ktx2")
except Exception as e:
print("WASM HDR backend ERROR:", e)
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