voxcity.simulator_gpu.solar.core¶

Vector and ray utilities for palm-solar using Taichi. Based on ray-tracing-one-weekend-taichi patterns.

GPU Optimization Notes: - All functions use @ti.func for GPU inlining - Branchless operations preferred where possible - Memory coalescing friendly access patterns - done-flag pattern for early termination (reduces warp divergence)

This module re-exports shared core utilities from simulator_gpu.core and adds solar-specific extensions.

Attributes¶

`Vector3`
`Point3`
`Color3`
`PI`
`TWO_PI`
`HALF_PI`
`DEG_TO_RAD`
`RAD_TO_DEG`
`SOLAR_CONSTANT`
`EXT_COEF`
`MIN_STABLE_COSZEN`
`GPU_BLOCK_SIZE`

Classes¶

`Rays`	Array of rays for batch processing.
`HitRecord`	Store ray-surface intersection results.

Functions¶

`normalize`(→ Vector3)	Normalize a vector.
`normalize_safe`(→ Vector3)	Normalize a vector with safety check for zero-length.
`dot`(→ taichi.f32)	Dot product of two vectors.
`cross`(→ Vector3)	Cross product of two vectors.
`reflect`(→ Vector3)	Reflect vector v around normal n.
`ray_at`(→ Point3)	Get point along ray at parameter t.
`length_squared`(→ taichi.f32)	Compute squared length of vector (avoids sqrt).
`distance_squared`(→ taichi.f32)	Compute squared distance between two points (avoids sqrt).
`min3`(→ taichi.f32)	Branchless minimum of three values.
`max3`(→ taichi.f32)	Branchless maximum of three values.
`clamp`(→ taichi.f32)	Clamp value to range [lo, hi].
`random_in_unit_sphere`(→ Vector3)	Generate random point in unit sphere.
`random_in_hemisphere`(→ Vector3)	Generate random vector in hemisphere around normal.
`random_cosine_hemisphere`(→ Vector3)	Generate random vector with cosine-weighted distribution in hemisphere.
`spherical_to_cartesian`(→ Vector3)	Convert spherical coordinates to Cartesian unit vector.
`cartesian_to_spherical`(→ taichi.math.vec2)	Convert Cartesian unit vector to spherical coordinates.
`rotate_vector_axis_angle`(→ Vector3)	Rotate vector around an axis by a given angle using Rodrigues' rotation formula.
`build_face_basis`(normal)	Build orthonormal basis for a face with given normal.

Module Contents¶

voxcity.simulator_gpu.solar.core.Vector3¶

voxcity.simulator_gpu.solar.core.Point3¶

voxcity.simulator_gpu.solar.core.Color3¶

voxcity.simulator_gpu.solar.core.PI = 3.141592653589793¶

voxcity.simulator_gpu.solar.core.TWO_PI = 6.283185307179586¶

voxcity.simulator_gpu.solar.core.HALF_PI = 1.5707963267948966¶

voxcity.simulator_gpu.solar.core.DEG_TO_RAD = 0.017453292519943295¶

voxcity.simulator_gpu.solar.core.RAD_TO_DEG = 57.29577951308232¶

voxcity.simulator_gpu.solar.core.SOLAR_CONSTANT = 1361.0¶

voxcity.simulator_gpu.solar.core.EXT_COEF = 0.6¶

voxcity.simulator_gpu.solar.core.MIN_STABLE_COSZEN = 0.0262¶

voxcity.simulator_gpu.solar.core.GPU_BLOCK_SIZE = 256¶

voxcity.simulator_gpu.solar.core.normalize(v: Vector3) → Vector3¶: Normalize a vector.

voxcity.simulator_gpu.solar.core.normalize_safe(v: Vector3) → Vector3¶: Normalize a vector with safety check for zero-length.

voxcity.simulator_gpu.solar.core.dot(v1: Vector3, v2: Vector3) → taichi.f32¶: Dot product of two vectors.

voxcity.simulator_gpu.solar.core.cross(v1: Vector3, v2: Vector3) → Vector3¶: Cross product of two vectors.

voxcity.simulator_gpu.solar.core.reflect(v: Vector3, n: Vector3) → Vector3¶: Reflect vector v around normal n.

voxcity.simulator_gpu.solar.core.ray_at(origin: Point3, direction: Vector3, t: taichi.f32) → Point3¶: Get point along ray at parameter t.

voxcity.simulator_gpu.solar.core.length_squared(v: Vector3) → taichi.f32¶: Compute squared length of vector (avoids sqrt).

voxcity.simulator_gpu.solar.core.distance_squared(p1: Point3, p2: Point3) → taichi.f32¶: Compute squared distance between two points (avoids sqrt).

voxcity.simulator_gpu.solar.core.min3(a: taichi.f32, b: taichi.f32, c: taichi.f32) → taichi.f32¶: Branchless minimum of three values.

voxcity.simulator_gpu.solar.core.max3(a: taichi.f32, b: taichi.f32, c: taichi.f32) → taichi.f32¶: Branchless maximum of three values.

voxcity.simulator_gpu.solar.core.clamp(x: taichi.f32, lo: taichi.f32, hi: taichi.f32) → taichi.f32¶: Clamp value to range [lo, hi].

voxcity.simulator_gpu.solar.core.random_in_unit_sphere() → Vector3¶: Generate random point in unit sphere.

voxcity.simulator_gpu.solar.core.random_in_hemisphere(normal: Vector3) → Vector3¶: Generate random vector in hemisphere around normal.

voxcity.simulator_gpu.solar.core.random_cosine_hemisphere(normal: Vector3) → Vector3¶: Generate random vector with cosine-weighted distribution in hemisphere. Used for diffuse radiation sampling.

voxcity.simulator_gpu.solar.core.spherical_to_cartesian(azimuth: taichi.f32, elevation: taichi.f32) → Vector3¶

Convert spherical coordinates to Cartesian unit vector.

Parameters:

azimuth – Angle from north (y-axis), clockwise, in radians
elevation – Angle from horizontal, in radians (0 = horizontal, pi/2 = zenith)

Returns:

Unit vector (x, y, z) where z is vertical (up)

voxcity.simulator_gpu.solar.core.cartesian_to_spherical(v: Vector3) → taichi.math.vec2¶

Convert Cartesian unit vector to spherical coordinates.

Returns:: vec2(azimuth, elevation) in radians

voxcity.simulator_gpu.solar.core.rotate_vector_axis_angle(vec: Vector3, axis: Vector3, angle: taichi.f32) → Vector3¶

Rotate vector around an axis by a given angle using Rodrigues’ rotation formula.

Parameters:

vec – Vector to rotate
axis – Rotation axis (will be normalized)
angle – Rotation angle in radians

Returns:

Rotated vector

voxcity.simulator_gpu.solar.core.build_face_basis(normal: Vector3)¶

Build orthonormal basis for a face with given normal.

Returns:: Tuple of (tangent, bitangent, normal) vectors