# ==============================================================================
# pyvale: the python validation engine
# License: MIT
# Copyright (C) 2026 Sceptical Rabbit (Lloyd Fletcher)
# ==============================================================================

"""Blender: Scene for 2D DIC
================================================================================

This example demonstrates how to set up and render a single camera 2D DIC
scene with Blender using the unified pyvale render API. The test case for this 
example is a solid mechanics finite element model of a plate with a hole loaded 
in tension.

Workflow:
1. Load simulation data, scale units, and create a textured surface mesh.
2. Create and position camera and lights.
3. Configure the Blender renderer backend.
4. Build the Scene3D, render the image, and save the Blender project file.
"""

from pathlib import Path

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

import pyvale.data as dataset
from pyvale import render
from pyvale.mooseherder import ExodusLoader
from pyvale.sensorsim import scale_length_units

# %%
# 1. Load simulation data and build a textured surface mesh
# --------------------------------------------------------------------------
# Load the mechanical plate with a hole simulation in Exodus format (``*.e``).
# All geometry and displacements are scaled to millimetres for Blender.
# Then convert the volumetric SimData into a surface Mesh3D. Volumetric meshes
# are skinned and conventions are enforced automatically.

data_path = dataset.render_mechanical_3d_path()
sim_data = ExodusLoader(data_path).load_all_sim_data()

disp_keys = ("disp_x", "disp_y", "disp_z")
sim_data = scale_length_units(1000.0, sim_data, disp_keys)

surface_mesh = render.meshes3d_from_simdata(
    sim_data,
    {"connect1": riley.ConnectConvention(
        riley.EElemType.TET4, riley.EConnectAxis.ROW, 0,
        riley.ENodeOrder.RILEY,
    )},
    displacement_keys=disp_keys,
)["connect1"]

# %%
# 2. Create and position camera and lights
# --------------------------------------------------------------------------
# Specify the physical sensor dimensions, sensor pixel grid, position,
# and focal length for a perspective camera.
camera = render.Camera(
    pixels_num=np.array((1540, 1040)),
    pixels_size=np.array((0.00345, 0.00345)),
    pos_world=np.array((0.0, 0.0, 400.0)),
    rot_world=Rotation.identity(),
    roi_cent_world=np.zeros(3),
    focal_length=15.0,
)

# Calculate camera resolution in mm/pixel to scale the speckle pattern.
resolution = render.blender_mm_per_pixel(camera)
surface_mesh.shader = render.BlenderTextureShader(
    image_path=dataset.dic_pattern_5mpx_path(),
    millimetres_per_pixel=resolution,
)

# Add a point light to illuminate the scene.
light = render.Light(
    light_type=render.ELightType.POINT,
    pos_world=np.array((0.0, 0.0, 400.0)),
    direction_world=np.zeros(3),
    intensity=1.0,
)

# %%
# 3. Configure and build the Blender renderer backend
# --------------------------------------------------------------------------
output_dir = Path.cwd() / "pyvale-output" / "render3d_ex2a_blender_scene"
config = render.BlenderConfig(
    output_dir=output_dir,
    samples=4,
    threads=8,
    save_images=True,
    save_scene=True,
)
renderer = render.Blender(config)

# %%
# 4. Build the Scene3D and render the image
# --------------------------------------------------------------------------
scene = render.Scene3D([surface_mesh], [camera], [light])
result = renderer.render(scene)

print(f"Rendered {len(result.output_paths)} image to disk.")
print(f"Output saved to: {output_dir}")

# %%
# The first rendered frame is shown below.
#
# .. image:: ../../../../_static/render3d_ex2a_blender_scene.png
#    :alt: Blender render of a speckled plate with a hole
#    :width: 500px
#    :align: center