336 lines
10 KiB
C++
336 lines
10 KiB
C++
#include "sc_sacd.h"
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// Standard library includes.
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#include <cmath>
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#include <stdfloat>
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#include <vector>
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// =============================================================================
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// Private Helpers BEGIN
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// =============================================================================
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constexpr float INV_SQRT2 = 0.70710678118654752440F;
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SC_SACD_Vec3 operator+(const SC_SACD_Vec3 &a, const SC_SACD_Vec3 &b) {
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return SC_SACD_Vec3{a.x + b.x, a.y + b.y, a.z + b.z};
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}
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SC_SACD_Vec3 operator-(const SC_SACD_Vec3 &a, const SC_SACD_Vec3 &b) {
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return SC_SACD_Vec3{a.x - b.x, a.y - b.y, a.z - b.z};
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}
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SC_SACD_Vec3 operator*(const SC_SACD_Vec3 &a, float scalar) {
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return SC_SACD_Vec3{a.x * scalar, a.y * scalar, a.z * scalar};
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}
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SC_SACD_Vec3 operator/(const SC_SACD_Vec3 &a, float scalar) {
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return SC_SACD_Vec3{a.x / scalar, a.y / scalar, a.z / scalar};
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}
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std::vector<SC_SACD_Vec3> SC_SACD_Get_Box_Normals(
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const SC_SACD_Generic_Box *box) {
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std::vector<SC_SACD_Vec3> normals;
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normals.emplace_back(SC_SACD_Vec3{1.0F, 0.0F, 0.0F});
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normals.back() = SC_SACD_Vec3_Rotate(normals.back(), box->x_radians,
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box->y_radians, box->z_radians);
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normals.emplace_back(SC_SACD_Vec3{0.0F, 1.0F, 0.0F});
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normals.back() = SC_SACD_Vec3_Rotate(normals.back(), box->x_radians,
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box->y_radians, box->z_radians);
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normals.emplace_back(SC_SACD_Vec3{0.0F, 0.0F, 1.0F});
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normals.back() = SC_SACD_Vec3_Rotate(normals.back(), box->x_radians,
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box->y_radians, box->z_radians);
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// Not normalizing the normals on purpose for optimization. (No unit vectors.)
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return normals;
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}
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std::vector<SC_SACD_Vec3> SC_SACD_Get_Box_Corners(
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const SC_SACD_Generic_Box *box) {
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std::vector<SC_SACD_Vec3> corners;
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SC_SACD_Vec3 pos{box->x, box->y, box->z};
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corners.push_back(
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SC_SACD_Vec3_Rotate(SC_SACD_Vec3{-box->width / 2.0F, -box->height / 2.0F,
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-box->depth / 2.0F},
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box->x_radians, box->y_radians, box->z_radians) +
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pos);
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corners.push_back(
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SC_SACD_Vec3_Rotate(SC_SACD_Vec3{box->width / 2.0F, -box->height / 2.0F,
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-box->depth / 2.0F},
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box->x_radians, box->y_radians, box->z_radians) +
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pos);
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corners.push_back(
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SC_SACD_Vec3_Rotate(SC_SACD_Vec3{-box->width / 2.0F, box->height / 2.0F,
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-box->depth / 2.0F},
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box->x_radians, box->y_radians, box->z_radians) +
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pos);
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corners.push_back(
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SC_SACD_Vec3_Rotate(SC_SACD_Vec3{box->width / 2.0F, box->height / 2.0F,
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-box->depth / 2.0F},
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box->x_radians, box->y_radians, box->z_radians) +
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pos);
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corners.push_back(
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SC_SACD_Vec3_Rotate(SC_SACD_Vec3{-box->width / 2.0F, -box->height / 2.0F,
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box->depth / 2.0F},
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box->x_radians, box->y_radians, box->z_radians) +
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pos);
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corners.push_back(
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SC_SACD_Vec3_Rotate(SC_SACD_Vec3{box->width / 2.0F, -box->height / 2.0F,
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box->depth / 2.0F},
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box->x_radians, box->y_radians, box->z_radians) +
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pos);
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corners.push_back(
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SC_SACD_Vec3_Rotate(SC_SACD_Vec3{-box->width / 2.0F, box->height / 2.0F,
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box->depth / 2.0F},
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box->x_radians, box->y_radians, box->z_radians) +
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pos);
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corners.push_back(
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SC_SACD_Vec3_Rotate(SC_SACD_Vec3{box->width / 2.0F, box->height / 2.0F,
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box->depth / 2.0F},
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box->x_radians, box->y_radians, box->z_radians) +
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pos);
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return corners;
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}
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struct SC_SACD_MinMax {
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float min, max;
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};
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std::vector<SC_SACD_MinMax> SC_SACD_Get_Box_MinMax(
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const SC_SACD_Generic_Box *box, const std::vector<SC_SACD_Vec3> &normals) {
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std::vector<SC_SACD_MinMax> minmaxes;
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std::vector<SC_SACD_Vec3> corners = SC_SACD_Get_Box_Corners(box);
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// Assuming normals are not normalized, and will not normalize anyway.
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// MinMax count should be same as normals count.
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for (const auto &normal : normals) {
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SC_SACD_MinMax minmax{INFINITY, -INFINITY};
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for (const auto &corner : corners) {
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float projected = SC_SACD_Dot_Product(corner, normal);
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if (projected > minmax.max) {
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minmax.max = projected;
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}
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if (projected < minmax.min) {
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minmax.min = projected;
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}
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}
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minmaxes.push_back(minmax);
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}
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return minmaxes;
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}
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// =============================================================================
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// Private Helpers END
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// =============================================================================
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int SC_SACD_AABB_Box_Collision(const SC_SACD_AABB_Box *a,
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const SC_SACD_AABB_Box *b) {
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float ax_min = a->x - a->width / 2.0F;
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float ax_max = a->x + a->width / 2.0F;
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float ay_min = a->y - a->height / 2.0F;
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float ay_max = a->y + a->height / 2.0F;
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float az_min = a->z - a->depth / 2.0F;
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float az_max = a->z + a->depth / 2.0F;
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float bx_min = b->x - b->width / 2.0F;
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float bx_max = b->x + b->width / 2.0F;
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float by_min = b->y - b->height / 2.0F;
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float by_max = b->y + b->height / 2.0F;
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float bz_min = b->z - b->depth / 2.0F;
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float bz_max = b->z + b->depth / 2.0F;
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return (ax_min < bx_max && ax_max > bx_min && ay_min < by_max &&
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ay_max > by_min && az_min < bz_max && az_max > bz_min)
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? 1
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: 0;
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}
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int SC_SACD_Generic_Box_Collision(const SC_SACD_Generic_Box *a,
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const SC_SACD_Generic_Box *b) {
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// Get all normals.
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std::vector<SC_SACD_Vec3> normals = SC_SACD_Get_Box_Normals(a);
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for (const auto &normal : SC_SACD_Get_Box_Normals(b)) {
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normals.push_back(normal);
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}
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// Get all minmaxes.
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std::vector<SC_SACD_MinMax> minmaxes_a = SC_SACD_Get_Box_MinMax(a, normals);
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std::vector<SC_SACD_MinMax> minmaxes_b = SC_SACD_Get_Box_MinMax(b, normals);
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// Check minmaxes.
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for (unsigned int i = 0; i < normals.size(); ++i) {
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if (minmaxes_a[i].max < minmaxes_b[i].min ||
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minmaxes_b[i].max < minmaxes_a[i].min) {
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return 0;
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}
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}
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return 1;
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}
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int SC_SACD_AABB_Generic_Box_Collision(const SC_SACD_AABB_Box *a,
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const SC_SACD_Generic_Box *b) {
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SC_SACD_Generic_Box a_conv;
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a_conv.x = a->x;
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a_conv.y = a->y;
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a_conv.z = a->z;
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a_conv.width = a->width;
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a_conv.height = a->height;
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a_conv.depth = a->depth;
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a_conv.x_radians = 0.0F;
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a_conv.y_radians = 0.0F;
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a_conv.z_radians = 0.0F;
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return SC_SACD_Generic_Box_Collision(&a_conv, b);
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}
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int SC_SACD_Sphere_Collision(const SC_SACD_Sphere *a, const SC_SACD_Sphere *b) {
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SC_SACD_Vec3 vec{a->x - b->x, a->y - b->y, a->z - b->z};
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return (a->radius + b->radius) > std::sqrt(SC_SACD_Dot_Product(vec, vec)) ? 1
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: 0;
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}
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int SC_SACD_Sphere_AABB_Box_Collision(const SC_SACD_Sphere *sphere,
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const SC_SACD_AABB_Box *box) {
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SC_SACD_Vec3 box_min{
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box->x - box->width / 2.0F,
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box->y - box->height / 2.0F,
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box->z - box->depth / 2.0F,
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};
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SC_SACD_Vec3 box_max{
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box->x + box->width / 2.0F,
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box->y + box->height / 2.0F,
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box->z + box->depth / 2.0F,
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};
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SC_SACD_Vec3 clamped{
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std::max(box_min.x, std::min(sphere->x, box_max.x)),
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std::max(box_min.y, std::min(sphere->y, box_max.y)),
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std::max(box_min.z, std::min(sphere->z, box_max.z))
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};
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SC_SACD_Vec3 diff = clamped - SC_SACD_Vec3{sphere->x, sphere->y, sphere->z};
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float dist = std::sqrt(SC_SACD_Dot_Product(diff, diff));
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return dist < sphere->radius;
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}
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int SC_SACD_Sphere_Box_Collision(const SC_SACD_Sphere *sphere,
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const SC_SACD_Generic_Box *box) {
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// TODO
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return 0;
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}
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float SC_SACD_Dot_Product(const SC_SACD_Vec3 a, const SC_SACD_Vec3 b) {
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return a.x * b.x + a.y * b.y + a.z * b.z;
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}
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SC_SACD_Vec3 SC_SACD_Cross_Product(const SC_SACD_Vec3 a, const SC_SACD_Vec3 b) {
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return SC_SACD_Vec3{a.y * b.z - a.z * b.y, a.z * b.x - a.x * b.z,
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a.x * b.y - a.y * b.x};
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}
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SC_SACD_Vec3 SC_SACD_Mat3_Vec3_Mult(const SC_SACD_Mat3 *mat,
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const SC_SACD_Vec3 vec) {
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return SC_SACD_Vec3{
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vec.x * mat->x0 + vec.y * mat->y0 + vec.z * mat->z0,
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vec.x * mat->x1 + vec.y * mat->y1 + vec.z * mat->z1,
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vec.x * mat->x2 + vec.y * mat->y2 + vec.z * mat->z2,
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};
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}
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SC_SACD_Vec3 SC_SACD_Vec3_Rotate(const SC_SACD_Vec3 vec, float x_axis,
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float y_axis, float z_axis) {
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/*
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* z_axis counter-clockwise affects x and y.
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* [ cos, -sin, 0 ]
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* [ sin, cos, 0 ]
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* [ 0, 0, 1 ]
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*
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* x_axis counter-clockwise affects y and z.
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* [ 1, 0, 0 ]
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* [ 0, cos, -sin ]
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* [ 0, sin, cos ]
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*
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* y_axis counter-clockwise affects x and z.
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* [ cos, 0, sin ]
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* [ 0, 1, 0 ]
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* [ -sin, 0, cos ]
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*/
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SC_SACD_Mat3 mat;
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SC_SACD_Vec3 result;
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// About x_axis.
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mat.x0 = 1.0F;
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mat.y0 = 0.0F;
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mat.z0 = 0.0F;
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mat.x1 = 0.0F;
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mat.y1 = std::cos(x_axis);
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mat.z1 = -std::sin(x_axis);
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mat.x2 = 0.0F;
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mat.y2 = -mat.z1;
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mat.z2 = mat.y1;
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result = SC_SACD_Mat3_Vec3_Mult(&mat, vec);
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// About y_axis.
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mat.x0 = std::cos(y_axis);
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mat.y0 = 0.0F;
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mat.z0 = std::sin(y_axis);
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mat.x1 = 0.0F;
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mat.y1 = 1.0F;
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mat.z1 = 0.0F;
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mat.x2 = -mat.z0;
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mat.y2 = 0.0F;
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mat.z2 = mat.x0;
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result = SC_SACD_Mat3_Vec3_Mult(&mat, result);
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// About z_axis.
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mat.x0 = std::cos(z_axis);
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mat.y0 = -std::sin(z_axis);
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mat.z0 = 0.0F;
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mat.x1 = -mat.y0;
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mat.y1 = mat.x0;
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mat.z1 = 0.0F;
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mat.x2 = 0.0F;
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mat.y2 = 0.0F;
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mat.z2 = 1.0F;
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return SC_SACD_Mat3_Vec3_Mult(&mat, result);
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}
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SC_SACD_Vec3 SC_SACD_Closest_Point_Dir_Normalized(const SC_SACD_Vec3 *pos,
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const SC_SACD_Vec3 *dir,
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const SC_SACD_Vec3 *point) {
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float alpha =
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SC_SACD_Dot_Product(*dir, *point) - SC_SACD_Dot_Product(*dir, *pos);
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return *pos + *dir * alpha;
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}
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SC_SACD_Vec3 SC_SACD_Closest_Point(const SC_SACD_Vec3 *pos,
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const SC_SACD_Vec3 *dir,
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const SC_SACD_Vec3 *point) {
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float alpha =
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(SC_SACD_Dot_Product(*dir, *point) - SC_SACD_Dot_Product(*dir, *pos)) /
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SC_SACD_Dot_Product(*dir, *dir);
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return *pos + *dir * alpha;
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}
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