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#include <SDL2/SDL.h>
#include <assert.h>
#include <stdlib.h>
#include "maths.cpp"
struct Shape {
v2f* points;
int count;
Shape(std::initializer_list<v2f> in) {
int i;
points = (v2f*)malloc(in.size() * sizeof *points);
count = in.size();
for (i = 0; i < count; i++)
points[i] = *(in.begin() + i);
}
Shape(const Shape& other) {
int s = other.count * sizeof *points;
count = other.count;
points = (v2f*)malloc(s);
memcpy(points, other.points, s);
}
~Shape() {
free(points);
}
void render(SDL_Renderer* ren) {
int i, c = count;
for (i = 0; i < c; i++) {
v2f a = points[i];
v2f b = points[(i + 1) % c];
SDL_RenderDrawLine(
ren,
(int)a.x,
(int)a.y,
(int)b.x,
(int)b.y
);
}
}
std::pair<v2f*, int> normals() const {
int c = (count >> 1) + 1, i;
v2f* normals = (v2f*)malloc(c * sizeof *normals);
for (i = 0; i < count; i++) {
v2f a = points[i];
v2f b = points[(i + 1) % count];
v2f e = a - b;
v2f n = v2f::normalised(v2f(e.y, -e.x));
normals[i] = n;
}
return { normals, i };
}
};
bool intersect(Shape& a, Shape& b) {
bool r = true;
int i;
auto[fn, fnc] = a.normals();
auto[sn, snc] = b.normals();
auto project = [](const Shape& shape, v2f axis) {
int i;
float mini = INFINITY;
float maxi = -INFINITY;
for (i = 0; i < shape.count; i++) {
v2f p = shape.points[i];
float d = v2f::dot(p, axis);
if (d < mini) mini = d;
if (d > maxi) maxi = d;
}
return std::pair<float, float>{ mini, maxi };
};
for (i = 0; i < fnc; i++) {
v2f axis = fn[i];
auto [fp1, fp2] = project(a, axis);
auto [sp1, sp2] = project(b, axis);
if (fp2 > sp1 && fp1 > sp2) {
r = false;
goto end;
}
}
for (i = 0; i < snc; i++) {
v2f axis = sn[i];
auto [fp1, fp2] = project(a, axis);
auto [sp1, sp2] = project(b, axis);
if (fp2 > sp1 && fp1 > sp2) {
r = false;
goto end;
}
}
end:
free(fn);
free(sn);
return r;
}
int main(int argc, const char** argv) {
int r = 1;
SDL_Window* window;
SDL_Renderer* ren;
SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_JOYSTICK);
SDL_CreateWindowAndRenderer(
800,
800,
0,
&window,
&ren
);
Shape a({
v2f(300.0f, 300.0f),
v2f(400.0f, 400.0f),
v2f(250.0f, 500.0f),
});
Shape tri({
v2f(0.0f, 0.0f),
v2f(50.0f, 200.0f),
v2f(200.0f, 100.0f),
});
while (r) {
int i;
SDL_Event e;
while (SDL_PollEvent(&e)) {
switch (e.type) {
case SDL_QUIT:
r = 0;
break;
}
}
int mx, my;
SDL_GetMouseState(&mx, &my);
Shape b(tri);
for (i = 0; i < b.count; i++) {
v2f& p = b.points[i];
p.x += mx;
p.y += my;
}
SDL_SetRenderDrawColor(ren, 0x00, 0x00, 0x00, 0x00);
SDL_RenderClear(ren);
SDL_SetRenderDrawColor(ren, 0xff, 0x00, 0xff, 0xff);
a.render(ren);
if (intersect(a, b)) {
SDL_SetRenderDrawColor(ren, 0xff, 0x00, 0x00, 0xff);
}
b.render(ren);
SDL_RenderPresent(ren);
}
SDL_DestroyRenderer(ren);
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}
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