#include "physics.h"

#include <stdlib.h>

#include <stdio.h>

#include <math.h>

#include "openglincludes.h"

#include "vector.h"

#include "body.h"

#include "unitcircle.h"

#define WIDTH 750

#define HEIGHT 750

#define TIMERMSECS 10

#define STEP 1.2

#define PATH_MOD(t) {if(t>=PATHLEN) t-=PATHLEN;}

Body *b;

int bodies;

double steps = 2.0;

int width = WIDTH;

int height = HEIGHT;

int oldwidth = WIDTH;

int oldheight = HEIGHT;

static Vector *unitCircle;

static size_t numUnitCircleVertices;

void init() {

srand(time(NULL));

numUnitCircleVertices = 64;

unitCircle = generateUnitCircle(numUnitCircleVertices);

b = (Body *)malloc(bodies*sizeof(Body));

int i;

for(i=0;i<bodies;++i) {

b[i] = newBody(

newVector(

1-2*(float)rand()/(float)RAND_MAX,

1-2*(float)rand()/(float)RAND_MAX

),

newVector(

0.002-0.004*(float)rand()/(float)RAND_MAX,

0.002-0.004*(float)rand()/(float)RAND_MAX

),

100*(float)rand()/(float)RAND_MAX

);

}

b[0] = newBody(newVector(0,0.0001),newVector(0,0),2000);

}

void timerFunc(int notUsed) {

glutPostRedisplay();

}

/* GL/GLUT stuff */

void keyPressed (unsigned char key, int x, int y) {

printf("%c\n",key);

if(key == 'f') {

#ifdef __FREEGLUT_STD_H__

glutFullScreenToggle();

#else

if(

glutGet(GLUT_WINDOW_WIDTH) == glutGet(GLUT_SCREEN_WIDTH) &&

glutGet(GLUT_WINDOW_HEIGHT) == glutGet(GLUT_SCREEN_HEIGHT) &&

glutGet(GLUT_WINDOW_X) == 0 &&

glutGet(GLUT_WINDOW_Y) == 0

) {

glutReshapeWindow(oldwidth,oldheight);

} else {

glutFullScreen();

}

#endif

}

if(key == 'q') {

#ifdef __FREEGLUT_STD_H__

glutLeaveMainLoop();

#else

exit(0);// lol

#endif

}

if(key == '+') {

steps *= STEP;

}

if(key == '-') {

steps /= STEP;

if(steps < 1) steps = 1;

}

if(key == '\x1e') {

// glutLeaveFullScreen();

}

}

void reshape (int w, int h) {

oldwidth = width;

oldheight = height;

width = w;

height = h;

glViewport(0, 0, (GLsizei)w, (GLsizei)h);

}

void display() {

glClear (GL_COLOR_BUFFER_BIT);

glLoadIdentity();

int k, j;

Body *bp;

Body *bBegin;

Body *bEnd;

//Colour red = {1.0,0.0,0.0,0.5};

glutTimerFunc(TIMERMSECS, timerFunc, 0);

bBegin = b + 1;

bEnd = b + bodies;

for(k = 0; k < (int)steps; ++k) {

for(bp = bBegin, j = 1; bp != bEnd; ++bp) {

bp->acceleration = move(bp, b, bodies);

}

for(bp = bBegin; bp != bEnd; ++bp) {

bp->velocity = vplus(&(bp->velocity), &(bp->acceleration));

bp->position = vplus(&(bp->position), &(bp->velocity));

bp->path.pos++;

PATH_MOD(bp->path.pos);

bp->path.point[bp->path.pos] = bp->position;

}

}

for(bp = b; bp != bEnd; ++bp) {

//if(collide(&(b[j]),b,bodies,j)) b[j].colour = red;

drawCircle(&(bp->position), sqrt(bp->mass), &(bp->colour));

traverse(bp);

}

glutSwapBuffers();

}

Vector coordToScreen(Vector *pos) {

Vector out = { pos->x*WIDTH/width, pos->y*HEIGHT/height };

return out;

}

void traverse(Body *b) {

int i,j;

glBegin(GL_LINE_STRIP);

for(i = 1; i<PATHLEN; i++) {

j = i+b->path.pos;

PATH_MOD(j);

Vector px = coordToScreen(&(b->path.point[j]));

glColor4f(

b->colour.r,

b->colour.g,

b->colour.b,

b->colour.a*((double)i)/((double)PATHLEN)

);

glVertex2f(px.x,px.y);

}

glEnd(); // GL_LINE_STRIP

}

void drawCircle(Vector *pos, double r, Colour *c) {

Vector sc = coordToScreen(pos);

r = fmax(r,2);

glMatrixMode(GL_MODELVIEW);

glPushMatrix();

//glLoadIdentity();

glTranslated(sc.x, sc.y, 0.0);

glScaled(r / width, r / height, 1.0);

glBegin(GL_POLYGON);

glColor4dv((double *)c);

int i;

for (i = 0; i < numUnitCircleVertices; ++i) {

glVertex2d(unitCircle[i].x, unitCircle[i].y);

}

glEnd(); // GL_POLYGON

glPopMatrix();

}

int main(int argc, char **argv) {

if(argc < 2) {

printf("Usage: %s numbodies\n",argv[0]);

return 1;

}

bodies = atoi(argv[1]);

init();

glutInit(&argc, argv);

glutInitDisplayMode (GLUT_DOUBLE | GLUT_ALPHA);

glutInitWindowSize (WIDTH, HEIGHT);

glutInitWindowPosition (0, 0);

glutCreateWindow("Yay physics");

glEnable(GL_BLEND);

glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

glClearColor (0.0,0.0,0.0,1.0);

glutDisplayFunc(display);

glutTimerFunc(TIMERMSECS, timerFunc, 0);

glutKeyboardFunc(keyPressed);

glutReshapeFunc(reshape);

glutMainLoop();

}