topaz/core/linear.c

/* SPDX-License-Identifier:BSD-3-Clause */
#include "linear.h"

float vec2_dot(vec2 a, vec2 b)
{
	float result = 0.0f;
	for (int i = 0; i < 2; i++) {
		result += a[i] * b[i];
	}

	return result;
}

float
vec3_dot(vec3 a, vec3 b)
{
	float result = 0.0f;
	for (int i = 0; i < 3; i++) {
		result += a[i] * b[i];
	}

	return result;
}

float
vec4_dot(vec4 a, vec4 b)
{
	float result = 0.0f;
	for (int i = 0; i < 4; i++) {
		result += a[i] * b[i];
	}

	return result;
}

void
vec3_cross(vec3 dest, vec3 a, vec3 b)
{
	vec3 res = {0};
	res[0] = a[1] * b[2] - a[2] * b[1];
	res[1] = a[2] * b[0] - a[0] * b[2];
	res[2] = a[0] * b[1] - a[1] * b[0];
	memcpy(dest, res, sizeof(vec3));
}

void
mat4_perspective(mat4 dest, float fov, float aspect, float near, float far)
{
	mat4 perspective = {
		{1.0f / (aspect * tan(fov / 2.0f)), 0.0f, 0.0f, 0.0f},
		{0.0f, 1.0f / tan(fov / 2.0f), 0.0f, 0.0f},
		{0.0f, 0.0f, -((far + near) / (far - near)), -((2 * far * near) / (far - near))},
		{0.0f, 0.0f, -1.0f, 0.0f}
	};

	memcpy(dest, perspective, sizeof(mat4));
}

void
mat4_lookat(mat4 dest, vec3 eye, vec3 target, vec3 up)
{
	vec3 target_cpy = {0};
	memcpy(target_cpy, target, sizeof(vec3));
	vec3_sub(target_cpy, target_cpy, eye);

	vec3 zaxis = {0};
	vec3_normalize(zaxis, target_cpy);

	vec3 zaxis_cpy = {0};
	memcpy(zaxis_cpy, zaxis, sizeof(vec3));
	vec3_cross(zaxis_cpy, zaxis, up);

	vec3 xaxis = {0};
	vec3_normalize(xaxis, zaxis_cpy);

	vec3 yaxis = {0};
	vec3_cross(yaxis, xaxis, zaxis);

	zaxis[0] = -zaxis[0];
	zaxis[1] = -zaxis[1];
	zaxis[2] = -zaxis[2];

	mat4 view = {
		{xaxis[0], xaxis[1], xaxis[2], -vec3_dot(xaxis, eye)},
		{yaxis[0], yaxis[1], yaxis[2], -vec3_dot(yaxis, eye)},
		{zaxis[0], zaxis[1], zaxis[2], -vec3_dot(zaxis, eye)},
		{0.0f, 0.0f, 0.0f, 1.0f}
	};

	memcpy(dest, view, sizeof(mat4));
}

void
vec2_sub(vec2 dest, vec2 a, vec2 b)
{
	vec2 res = {0};
	for (int i = 0; i < 2; i++)
		res[i] = a[i] - b[i];
	memcpy(dest, res, sizeof(vec2));
}

void
vec3_sub(vec3 dest, vec3 a, vec3 b)
{
	vec3 res = {0};
	for (int i = 0; i < 3; i++)
		res[i] = a[i] - b[i];
	memcpy(dest, res, sizeof(vec3));
}

void
vec4_sub(vec4 dest, vec4 a, vec4 b)
{
	vec4 res = {0};
	for (int i = 0; i < 4; i++)
		res[i] = a[i] - b[i];
	memcpy(dest, res, sizeof(vec4));
}

void
vec2_add(vec2 dest, vec2 a, vec2 b)
{
	vec2 res = {0};
	for (int i = 0; i < 2; i++)
		res[i] = a[i] + b[i];
	memcpy(dest, res, sizeof(vec2));
}

void
vec3_add(vec3 dest, vec3 a, vec3 b)
{
	vec3 res = {0};
	for (int i = 0; i < 3; i++)
		res[i] = a[i] + b[i];
	memcpy(dest, res, sizeof(vec3));
}

void
vec4_add(vec4 dest, vec4 a, vec4 b)
{
	vec4 res = {0};
	for (int i = 0; i < 4; i++)
		res[i] = a[i] + b[i];
	memcpy(dest, res, sizeof(vec4));
}

void
vec2_normalize(vec2 dest, vec2 a)
{
	vec2 res = {0};
	memcpy(res, a, sizeof(vec2));
	float w = sqrt(a[0] * a[0] + a[1] * a[1]);
	res[0] /= w;
	res[1] /= w;
	memcpy(dest, res, sizeof(vec2));
}

void
vec3_normalize(vec3 dest, vec3 a)
{
	vec3 res = {0};
	memcpy(res, a, sizeof(vec3));
	float w = sqrt(a[0] * a[0] + a[1] * a[1] + a[2] * a[2]);
	res[0] /= w;
	res[1] /= w;
	res[2] /= w;
	memcpy(dest, res, sizeof(vec3));
}

void
vec4_normalize(vec4 dest, vec4 a)
{
	vec4 res = {0};
	memcpy(res, a, sizeof(vec4));
	float w = sqrt(a[0] * a[0] + a[1] * a[1] + a[2] * a[2]);
	res[0] /= w;
	res[1] /= w;
	res[2] /= w;
	res[3] /= w;
	memcpy(dest, res, sizeof(vec4));
}

void
vec2_scale(vec2 dest, vec2 a, float scale)
{
	memcpy(dest, a, sizeof(vec2));
	for (int i = 0; i < 2; i++)
		dest[i] *= scale;
}

void
vec3_scale(vec3 dest, vec3 a, float scale)
{
	memcpy(dest, a, sizeof(vec3));
	for (int i = 0; i < 3; i++)
		dest[i] *= scale;
}

void
vec4_scale(vec4 dest, vec4 a, float scale)
{
	memcpy(dest, a, sizeof(vec4));
	for (int i = 0; i < 4; i++)
		dest[i] *= scale;
}