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particules.c
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particules.c
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#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include <SDL2/SDL.h>
#include <SDL2/SDL_mixer.h>
// #define FPS 600
#define WIDTH 256
#define HEIGHT 256
#define pNum 5000
typedef struct particle_t {
float x, y;
float r;
float m;
SDL_Color c;
float speedX;
float speedY;
} particule;
inline SDL_bool collide(particule *p1, particule *p2) {
return (p2->x - p1->x)*(p2->x - p1->x) + (p2->y - p1->y)*(p2->y - p1->y) <= 4; // all particules have a radius of 1
// return (p2->x - p1->x)*(p2->x - p1->x) + (p2->y - p1->y)*(p2->y - p1->y) <= (p1->r + p2->r)*(p1->r + p2->r);
// return(abs(p2->x - p1->x)<=2 && abs(p2->y - p1->y) <=2);
}
void SDL_RenderDrawParticule(SDL_Renderer *renderer, particule *p) {
SDL_SetRenderDrawColor(renderer, p->c.r, p->c.g, p->c.b, p->c.a);
SDL_RenderDrawPoint(renderer, p->x, p->y);
}
int main(int argc, char *argv[]) {
// const int frameDelay = 1000 / FPS;
// Uint32 frameStart, frameTime;
float friction = .99;
float gravity = .04;
float elasticity = .8;
particule p[pNum] = {{0}};
float newVelX1, newVelY1;
float newVelX2, newVelY2;
float collisionPointX, collisionPointY;
srand(time(NULL));
SDL_Init(SDL_INIT_VIDEO);
SDL_Window *window = SDL_CreateWindow("particules", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, WIDTH, HEIGHT, SDL_WINDOW_OPENGL);
SDL_Renderer *renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
SDL_bool isRunning = SDL_TRUE;
SDL_Event event;
for(int i=0; i<pNum; i++){
p[i].m = 12;
p[i].r = 60;
p[i].x = rand()%WIDTH;
p[i].y = rand()%HEIGHT;
p[i].c.r = rand()%155+100;
p[i].c.g = rand()%155+100;
p[i].c.b = rand()%155+100;
p[i].c.a = 255;
p[i].speedX = (float)(rand()%1000) / 100.0 - 5.0;
p[i].speedY = (float)(rand()%1000) / 100.0 - 5.0;
// for (int j = 0; j < i; j++) {
// if (collide(p[i], p[j])){
// i--;
// break;
// }
// }
}
while(isRunning) {
// frameStart = SDL_GetTicks();
SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
SDL_RenderClear(renderer);
while(SDL_PollEvent(&event))
if (event.type == SDL_QUIT || event.type == SDL_KEYDOWN) isRunning = SDL_FALSE;
for(int i = 0; i < pNum; i++){
// add gravity
p[i].speedY += gravity;
// add friction
p[i].speedX *= friction;
p[i].speedY *= friction;
if (p[i].speedX > -.01 && p[i].speedX < .01 )
p[i].speedX = 0;
if (p[i].speedY > -.01 && p[i].speedY < .01 )
p[i].speedY = 0;
p[i].x += p[i].speedX; // update position
p[i].y += p[i].speedY;
}
for(int i=0; i<pNum; i++) { // bounce each other
for (int j=0; j<i; j++) {
if(collide(&p[i], &p[j])) {
collisionPointX = ((p[i].x * p[j].r) + (p[j].x * p[i].r)) / (p[i].r + p[j].r);
collisionPointY = ((p[i].y * p[j].r) + (p[j].y * p[i].r)) / (p[i].r + p[j].r);
SDL_SetRenderDrawColor(renderer, 255, 0, 255, 255);
SDL_RenderDrawPoint(renderer, collisionPointX, collisionPointY);
// the collision point might be INSIDE the balls - they are overlapping
float angle = atan2f(p[i].y - p[j].y, p[i].x - p[j].x);
float distanceBetweenCircles = sqrt( (p[i].x - p[j].x) * (p[i].x - p[j].x) + (p[i].y - p[j].y) * (p[i].y - p[j].y) );
float distanceToMove = p[j].r + p[i].r - distanceBetweenCircles;
p[i].x += cos(angle) * distanceToMove;
p[i].y += sin(angle) * distanceToMove;
newVelX1 = (p[i].speedX * (p[i].r - p[j].r) + (2 * p[j].r * p[j].speedX)) / (p[i].r + p[j].r);
newVelY1 = (p[i].speedY * (p[i].r - p[j].r) + (2 * p[j].r * p[j].speedY)) / (p[i].r + p[j].r);
newVelX2 = (p[j].speedX * (p[j].r - p[i].r) + (2 * p[i].r * p[i].speedX)) / (p[i].r + p[j].r);
newVelY2 = (p[j].speedY * (p[j].r - p[i].r) + (2 * p[i].r * p[i].speedY)) / (p[i].r + p[j].r);
p[i].speedX = newVelX1*elasticity;
p[i].speedY = newVelY1*elasticity;
p[j].speedX = newVelX2*elasticity;
p[j].speedY = newVelY2*elasticity;
p[i].x += p[i].speedX;
p[i].y += p[i].speedY;
p[j].x += p[j].speedX;
p[j].y += p[j].speedY;
}
}
}
for(int i = 0; i < pNum; i++){ // bounce on borders
if (p[i].x < p[i].r) {
p[i].speedX *= -elasticity;
p[i].x = p[i].r;
}
if (p[i].x > WIDTH - p[i].r) {
p[i].speedX *= -elasticity;
p[i].x = WIDTH - p[i].r;
}
if (p[i].y < p[i].r) {
p[i].speedY *= -elasticity;
p[i].y = p[i].r;
}
if (p[i].y > HEIGHT - p[i].r) {
p[i].speedY *= -elasticity;
p[i].y = HEIGHT - p[i].r;
}
}
// for(int i=0; i<pNum; i++)
// SDL_RenderDrawParticule(renderer, &p[i]);
// frameTime = SDL_GetTicks() - frameStart;
// if (frameDelay > frameTime ) SDL_Delay(frameDelay - frameTime);
SDL_RenderPresent(renderer);
}
SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(window);
SDL_Quit();
exit(EXIT_SUCCESS);
}