From 3c0a3b8413ee58a3e5678075c862e95f7c8395c6 Mon Sep 17 00:00:00 2001
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Date: Mon, 27 Mar 2023 11:25:27 +0300
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---
 simulations/boids.c | 237 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 237 insertions(+)
 create mode 100644 simulations/boids.c

(limited to 'simulations/boids.c')

diff --git a/simulations/boids.c b/simulations/boids.c
new file mode 100644
index 0000000..84afc21
--- /dev/null
+++ b/simulations/boids.c
@@ -0,0 +1,237 @@
+#ifdef _WIN32 // грубый способ определения; на деле разница не в ОС, а в компиляторe
+	#include <SDL.h>
+	#include <SDL_image.h>
+	#include <SDL_timer.h>
+#else
+	#include <SDL2/SDL.h>
+	#include <SDL2/SDL_image.h>
+	#include <SDL2/SDL_timer.h>
+#endif
+#include <time.h>
+#include <math.h>
+
+#define SCALE 	1
+#define BOIDNUM 30
+#define SPEED	1
+#define CRANGE 	30
+#define WIDTH	1280
+#define HEIGHT 	640
+#define PI 		3.1415926535
+
+struct boid { double x, y, dx, dy, th; };
+typedef struct vec { float x, y; } vector;
+struct boid B[BOIDNUM];
+char color[3] = {0, 255, 0};
+
+int init() 
+{
+	srand(time(NULL));
+
+	for(int i = 0; i<BOIDNUM; i++) {
+		B[i].x =  WIDTH/2  + rand() % 128 - 64; 
+		B[i].y =  HEIGHT/2 + rand() % 128 - 64;
+		B[i].th = rand() / (float)RAND_MAX * (PI/3) - PI/6;
+		B[i].dx = SPEED * cos(B[i].th); 
+		B[i].dy = SPEED * sin(B[i].th);
+		// printf("%f",B[i].th);
+	}
+
+	return 0;
+}
+
+int processEvents(SDL_Window *window) 
+{
+	SDL_Event event;
+
+	while(SDL_PollEvent(&event))
+	{
+		switch(event.type)
+		{	
+			case SDL_WINDOWEVENT_CLOSE:
+				if(window)
+				{
+					SDL_DestroyWindow(window);
+					window = NULL;
+					return 1;
+				}
+				break;
+			
+			case SDL_KEYDOWN:
+				switch(event.key.keysym.sym) {
+					case SDLK_ESCAPE:
+						return 1;
+				}
+		}
+	}
+	return 0;
+}
+
+void render(SDL_Renderer *renderer) 
+{
+	SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); // фон
+	SDL_RenderClear(renderer);
+
+	SDL_Vertex arrow[BOIDNUM][3];
+	for(int i = 0; i<BOIDNUM; i++) {
+		arrow[i][0].position.x = (B[i].x+7 *cos(B[i].th-PI/2))/SCALE;
+		arrow[i][0].position.y = (B[i].y+7 *sin(B[i].th-PI/2))/SCALE;
+		arrow[i][1].position.x = (B[i].x+7 *cos(B[i].th+PI/2))/SCALE;
+		arrow[i][1].position.y = (B[i].y+7 *sin(B[i].th+PI/2))/SCALE;
+		arrow[i][2].position.x = (B[i].x+20*cos(B[i].th))	  /SCALE;
+		arrow[i][2].position.y = (B[i].y+20*sin(B[i].th))	  /SCALE;
+	
+		for(int j = 0; j<3; j++) {
+			arrow[i][j].color.r = color[0];
+			arrow[i][j].color.g = color[1]+j*25;
+			arrow[i][j].color.b = color[2];
+			arrow[i][j].color.a = 255;
+		}
+	SDL_RenderGeometry(renderer, NULL, arrow[i], 3, NULL, 0);
+	}
+
+	SDL_RenderPresent(renderer);
+}
+
+float geomdist(int i, int j)
+{
+	return sqrt(pow( B[i].x - B[j].x, 2 ) + pow( B[i].y - B[j].y, 2 ));
+}
+
+vector cohesion(int n, int factor) 
+{
+	vector sum = {0, 0};
+	for(int b = 0; b < BOIDNUM; b++) {
+		if(geomdist(n, b) > CRANGE) {continue;}
+		if(b == n) {continue;}
+		sum.x += B[b].x;
+		sum.y += B[b].y;
+	}
+
+	sum.x /= BOIDNUM - 1;
+	sum.y /= BOIDNUM - 1;
+
+	sum.x -= B[n].x;
+	sum.y -= B[n].y;
+	sum.x /= factor;
+	sum.y /= factor;
+
+	return sum;
+}
+
+vector separation(int n, float dist, int factor)
+{
+	vector c = {0, 0};
+	c.x = 0;
+	c.y = 0;
+
+	for(int b = 0; b < BOIDNUM; b++) {
+		if(geomdist(n, b) > CRANGE) {continue;}
+		if(b == n) {continue;}
+		if(geomdist(n, b) < dist) {
+			c.x -= B[b].x - B[n].x;
+			c.y -= B[b].y - B[n].y;
+		}
+	}
+
+	c.x /= factor;
+	c.y /= factor;
+
+	return c;
+}
+
+vector alignment(int n, int factor)
+{
+	vector pv = {0, 0};
+
+	for(int b = 0; b < BOIDNUM; b++) {
+		if(geomdist(n, b) > CRANGE) {continue;}
+		if(b == n) {continue;}
+		pv.x += B[b].dx;
+		pv.y += B[b].dy;
+	}
+
+	pv.x /= BOIDNUM - 1;
+	pv.y /= BOIDNUM - 1;
+
+	pv.x -= B[n].dx;
+	pv.y -= B[n].dy;
+	pv.x /= factor;
+	pv.y /= factor;
+
+	return pv;
+}
+
+int updatePos(SDL_Renderer *renderer) {
+	vector v[3];
+	for(int i = 0; i<BOIDNUM; i++) {
+		B[i].x += B[i].dx;
+		B[i].y += B[i].dy;
+		// B[i].th += PI/72;
+		if(B[i].x > WIDTH)
+			B[i].x -= WIDTH;
+			// B[i].dx = 0;
+		if(B[i].y > HEIGHT)
+			B[i].y -= HEIGHT;
+			// B[i].dy = 0;
+		if(B[i].x < 0)
+			B[i].x += WIDTH;
+			// B[i].dx = 0;
+		if(B[i].y < 0)
+			B[i].y += HEIGHT;
+			// B[i].dy = 0;
+
+		v[0] = cohesion(i, 40);
+		v[1] = separation(i, 20, 200);
+		// v[0].x = 0;
+		// v[0].y = 0;
+		v[2] = alignment(i, 80);
+		// v[2].x = 0;
+		// v[2].y = 0;
+
+		for(int j = 0; j<3; j++) {
+			if(i == 0) {
+				SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255);
+				SDL_RenderDrawLine(renderer, B[i].x, B[i].y, B[i].x-v[j].x, B[i].y - v[j].y);
+				SDL_RenderPresent(renderer);
+				printf("|vx = %f, vy = %f", v[j].x, v[j].y);
+			}
+
+			B[i].dx += v[j].x / 1000;
+			B[i].dy += v[j].y / 1000;
+		}
+		// if (B[i].dx > sqrt(50)) B[i].dx = sqrt(50);
+		// if (B[i].dy > sqrt(50)) B[i].dy = sqrt(50);
+		B[i].th = acos(B[i].dx / sqrt(B[i].dx * B[i].dx + B[i].dy * B[i].dy) + 0.0001);
+		// if(i == 0) {
+			// printf("%f|", B[i].th);
+		// }
+	}
+	return 0;
+}
+
+int main(int argc, char *argv[]) 
+{
+	SDL_Window *window = NULL;
+	SDL_Renderer *renderer = NULL;
+
+	init();
+	SDL_Init(SDL_INIT_VIDEO);
+
+	window = SDL_CreateWindow("Boids",
+				  SDL_WINDOWPOS_CENTERED,
+				  SDL_WINDOWPOS_CENTERED,
+				  WIDTH,
+				  HEIGHT,
+				  0);
+	renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
+
+	while(1) {
+		if(processEvents(window) == 1)
+			break;
+		render(renderer);
+		updatePos(renderer);
+		SDL_Delay(10);
+	}
+
+	return 0;
+}
\ No newline at end of file
-- 
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