Core Module

Basic data types and utility functions for the ray tracer.

vec3

3D vector class with common operations.

struct vec3 {
    float x, y, z;

    __host__ __device__ vec3 operator+(const vec3& v) const;
    __host__ __device__ vec3 operator-(const vec3& v) const;
    __host__ __device__ vec3 operator*(float t) const;
    __host__ __device__ float dot(const vec3& v) const;
    __host__ __device__ vec3 cross(const vec3& v) const;
    __host__ __device__ float length() const;
    __host__ __device__ vec3 normalize() const;
};

Common Operations:

Operation	Description
dot(a, b)	Dot product: $a \cdot b$
cross(a, b)	Cross product: $a \times b$
reflect(v, n)	Reflection: $v - 2(v \cdot n)n$
normalize(v)	Unit vector: $v / |v|$

ray

Ray class with origin and direction.

struct ray {
    vec3 origin;      // Ray starting point
    vec3 direction;   // Normalized direction
    float t_min;      // Minimum intersection distance
    float t_max;      // Maximum intersection distance

    __host__ __device__ vec3 at(float t) const {
        return origin + direction * t;
    }
};

Random Utilities

CUDA random number utilities using cuRAND.

// Initialize random state per pixel
__device__ void init_random(curandState* state, int seed);

// Generate uniform [0, 1)
__device__ float random_float(curandState* state);

// Generate uniform [min, max)
__device__ float random_float(curandState* state, float min, float max);

// Cosine-weighted hemisphere sampling
__device__ vec3 random_cosine_direction(curandState* state);

// Uniform sphere sampling
__device__ vec3 random_in_unit_sphere(curandState* state);

CUDA Helper Macro

// CUDA error checking
#define CUDA_CHECK(call) \
    do { \
        cudaError_t err = call; \
        if (err != cudaSuccess) { \
            fprintf(stderr, "CUDA Error at %s:%d: %s\n", \
                    __FILE__, __LINE__, cudaGetErrorString(err)); \
            exit(1); \
        } \
    } while (0)

Constants

namespace constants {
    constexpr float PI = 3.14159265358979323846f;
    constexpr float EPSILON = 1e-6f;
    constexpr float INFINITY = 1e30f;
    constexpr int MAX_DEPTH = 64;  // BVH max depth
}

Usage Example

// Vector operations
vec3 a(1.0f, 2.0f, 3.0f);
vec3 b(4.0f, 5.0f, 6.0f);
vec3 c = a + b;              // (5, 7, 9)
float d = dot(a, b);         // 32
vec3 e = cross(a, b);        // (-3, 6, -3)

// Ray operations
Ray r(vec3(0, 0, 0), normalize(vec3(1, 1, 0)));
vec3 p = r.at(5.0f);         // Point at t=5