init: first commit - rendering triangle

fastmath.hpp

@@ -0,0 +1,140 @@
+#ifndef FASTMATH_H
+#define FASTMATH_H
+
+#include <cmath>
+#include <iostream>
+#include <stdint.h>
+#include <stdlib.h>
+#define SHIFT_AMOUNT 16
+#define HALF_SHIFT (SHIFT_AMOUNT / 2)
+
+#define SHIFT_MASK ((1 << SHIFT_AMOUNT) - 1)
+#define TO_FLOAT(x)                                                            \
+    (((float)(x >> SHIFT_AMOUNT)) +                                            \
+     ((double)(x & SHIFT_MASK) / (1 << SHIFT_AMOUNT)))
+#define TO_INT(x) ((int32_t)(x * (1 << SHIFT_AMOUNT)))
+#define MUL_F(a, b) (((a) >> HALF_SHIFT) * ((b) >> HALF_SHIFT))
+#define DIV_F(a, b) ((((a) << HALF_SHIFT) / (b)) << HALF_SHIFT)
+
+struct decimal {
+
+    const int32_t i;
+
+    decimal(float i) : i(TO_INT(i)) {}
+    decimal(double i) : i(TO_INT(i)) {}
+    decimal(int32_t i) : i(i) {}
+
+    friend std::ostream &operator<<(std::ostream &os, const decimal &d) {
+        return (os << TO_FLOAT(d.i));
+    }
+
+    friend decimal operator+(const decimal &d1, const decimal &d2) {
+        return {d1.i + d2.i};
+    }
+    decimal &operator+=(const decimal &d) { return (*this) = {i + d.i}; }
+
+    friend decimal operator-(const decimal &d1, const decimal &d2) {
+        return {d1.i - d2.i};
+    }
+    friend decimal operator-(const decimal &d) { return {-d.i}; }
+
+    friend decimal operator*(const decimal &d1, const decimal &d2) {
+        return {MUL_F(d1.i, d2.i)};
+    }
+
+    friend decimal operator/(const decimal &d1, const decimal &d2) {
+        return {DIV_F(d1.i, d2.i)};
+    }
+
+    friend bool operator<(const decimal &d1, const decimal &d2) {
+        return d1.i < d2.i;
+    }
+
+    friend bool operator>(const decimal &d1, const decimal &d2) {
+        return d1.i > d2.i;
+    }
+
+    friend bool operator==(const decimal &d1, const decimal &d2) {
+        return d1.i == d2.i;
+    }
+
+    decimal &operator=(decimal const &in) {
+        if (this != &in) {
+            std::destroy_at(this);
+            std::construct_at(this, in);
+        }
+        return *this;
+    }
+
+    decimal sqrt() { return {((int32_t)sqrtf(i)) << HALF_SHIFT}; }
+
+    float to_float() { return TO_FLOAT(i); }
+};
+
+struct vec3 {
+    const decimal x;
+    const decimal y;
+    const decimal z;
+
+    vec3(float x, float y, float z)
+        : x(decimal(x)), y(decimal(y)), z(decimal(z)) {}
+
+    vec3(double x, double y, double z)
+        : x(decimal(x)), y(decimal(y)), z(decimal(z)) {}
+
+    vec3(int32_t x, int32_t y, int32_t z)
+        : x(decimal(x)), y(decimal(y)), z(decimal(z)) {}
+    vec3(decimal x, decimal y, decimal z) : x(x), y(y), z(z) {}
+
+    friend vec3 operator+(const vec3 &v1, const vec3 &v2) {
+        return vec3(v1.x + v2.x, v1.y + v2.y, v1.z + v2.z);
+    }
+
+    friend vec3 operator-(const vec3 &v1, const vec3 &v2) {
+        return vec3(v1.x - v2.x, v1.y - v2.y, v1.z - v2.z);
+    }
+
+    vec3 operator-() { return vec3(-x, -y, -z); }
+
+    friend vec3 operator*(const vec3 &v, const decimal &n) {
+        int32_t f = n.i >> HALF_SHIFT;
+        return vec3({(v.x.i >> HALF_SHIFT) * f}, {(v.y.i >> HALF_SHIFT) * f},
+                    {(v.z.i >> HALF_SHIFT) * f});
+    }
+    friend vec3 operator*(const decimal &n, const vec3 &v) { return v * n; }
+
+    decimal operator*(const vec3 &v) { return v.x * x + v.y * y + v.z * z; }
+
+    friend bool operator==(const vec3 &v1, const vec3 &v2) {
+        return (v1.x == v2.x) & (v1.y == v2.y) & (v1.z == v2.z);
+    }
+
+    vec3 &operator=(vec3 const &in) {
+        if (this != &in) {
+            std::destroy_at(this);
+            std::construct_at(this, in);
+        }
+        return *this;
+    }
+
+    friend std::ostream &operator<<(std::ostream &os, const vec3 &v) {
+        return (os << "(" << v.x << ", " << v.y << ", " << v.z << ")"
+                   << std::endl);
+    }
+
+    vec3 cross(const vec3 &v) {
+        return vec3((y * v.z) - (z * v.y), (z * v.x) - (x * v.z),
+                    (x * v.y) - (y * v.x));
+    }
+
+    decimal len_sq() { return *this * *this; }
+
+    decimal len() { return this->len_sq().sqrt(); }
+
+    vec3 normalize() {
+        decimal f = decimal(1.0) / this->len();
+        return (*this * f);
+    }
+};
+
+#endif