# ==============================================================================
# pyvale: the python validation engine
# License: MIT
# Copyright (C) 2025 The Computer Aided Validation Team
# ==============================================================================

"""
Riley: Speckle sphere
================================================================================
Here we render a sphere mesh of TRI6 elements with a speckle pattern texture 
shader. 

Texture shaders use a 2D image and wrap this around a 3D object using normalised
coordinates called UVs in computer graphics. The texture shader itself then 
uses these UV coordinates to map into and interpolate the colour for a pixel.

The quality of the reconstruction is dependent on the resolution of the texture
relative to the final camera image size, the texture sampling function and the
pixel integration parameters (i.e. pixel subsampling).  

It is common to want to map a speckle pattern onto a 3D surface using UV
coordinates for digital image correlation simulation. We provide a set of 
examples on UV mapping for common cases in the "Render UVs" example gallery.

There are also much more advanced tools for UV mapping in Blender if you require them.
"""

from pathlib import Path

import numpy as np
import riley
from scipy.spatial.transform import Rotation

import pyvale.data as dataset
import pyvale.dataio as io
from pyvale import render

# %%
# 1. Load the mesh and assign a texture shader
# ------------------------------------------------------------
data_dir: Path = dataset.riley_sphere200_case_path()

simulation = io.MeshLoader(
    load_dir=data_dir,
    coords_file="coords.csv",
    connect_files="connect.csv",
    load_opts=io.SimLoadOpts(coord_header=None),
).load_mesh()

uvs = io.load_array(data_dir / "uvs.csv", header=None, delimiter=",")

texture = riley.load_texture_mono_u8(dataset.riley_speckle_texture_path())

shader = riley.TextureShader(uvs=uvs, texture=texture)

mesh = render.meshes3d_from_simdata(
    simulation,
    {"connect": riley.ConnectConvention(
        riley.EElemType.TRI6, riley.EConnectAxis.ROW, 0,
        riley.ENodeOrder.RILEY,
    )},
    shaders={"connect": shader},
)["connect"]

# %%
# 2. Create and position the camera
# ------------------------------------------------------------

pixels_num = np.array((800, 500))
pixels_size = np.array((5.3e-6, 5.3e-6))
focal_length = 50.0e-3
rotation = Rotation.identity()

camera = render.Camera(
    pixels_num=pixels_num,
    pixels_size=pixels_size,
    pos_world=np.zeros(3),
    rot_world=rotation,
    roi_cent_world=np.zeros(3),
    focal_length=focal_length,
    subsample=2,
)

camera = render.cam_frame_mesh(camera, mesh, fov_scale=1.0)

# %%
# 3. Configure and build the renderer
# ------------------------------------------------------------

config = riley.create_raster_config(
    num_frames=1,
    total_threads=4,
    save_strategy=riley.SaveStrategy.disk,
)
output_dir = Path.cwd() / "pyvale-output" / "render3d_ex1b_riley_sphere200"

renderer = render.Riley(config, output_dir)

# %%
# 4. Build the scene and render it
# ------------------------------------------------------------
scene = render.Scene3D(meshes=[mesh], cameras=[camera])
result = renderer.render(scene)

print(f"Rendered sphere render output to {output_dir}")
print(f"{result.images=}")

# %%
# The first rendered frame is shown below.
#
# .. image:: ../../../../_static/render3d_ex1b_riley_sphere200.png
#    :alt: A sphere with a speckle pattern
#    :width: 500px
#    :align: center