137 lines
2.6 KiB
C
137 lines
2.6 KiB
C
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#include <unistd.h>
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#include "graphics.h"
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#define FRAMERATE 60
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#define GRAVITY 0.001f
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// Points store position, position in previous frame and forces
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// velocity is calculated from the distance between (x,y) and (px,py)
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typedef struct Point{
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double x, y,
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px, py,
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fx, fy;
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} Point;
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// Links connect two points such that their distance is constant
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// these can be used to make rigid bodies
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typedef struct Link {
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Point* a;
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Point* b;
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double length;
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} Link;
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/*
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* Function declarations
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*/
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Link* link_points(Point* a, Point* b);
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void draw_link(Canvas* c, Link* l);
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void update_point(Point* p);
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/*
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* Main
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*/
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int main(){
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char *data = malloc(40*40);
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Canvas cnv = {40, 40, data};
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// Add 4 points, link them, and add points and links to respective arrays
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Point a = { 10.0, 10.0,
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10.0, 10.0,
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0.0, GRAVITY/FRAMERATE};
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Point b = { 20.0, 10.0,
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20.0, 10.0,
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0.0, GRAVITY/FRAMERATE};
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Point c = { 20.0, 20.0,
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20.0, 20.0,
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0.0, GRAVITY/FRAMERATE};
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Point d = { 10.0, 20.0,
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10.0, 20.0,
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0.0, GRAVITY/FRAMERATE};
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Link *l_ab = link_points(&a, &b);
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Link *l_bc = link_points(&b, &c);
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Link *l_cd = link_points(&c, &d);
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Link *l_ad = link_points(&a, &d);
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Point *points[] = {&a, &b, &c, &d};
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Link *links[] = {l_ab, l_bc, l_cd, l_ad};
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while(1){
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// clear canvas, calculate next frame and draw
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memset(cnv.data, '.', cnv.x * cnv.y);
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for(int i=0; i<4; i++)
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draw_link(&cnv, links[i]);
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for(int i=0; i<4; i++)
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update_point(points[i]);
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// then render and wait
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render(&cnv);
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usleep(1000000/FRAMERATE);
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}
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return 0;
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}
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// Returns distance of two points
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double distance(Point* a, Point* b){
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double dx = a->x - b->x;
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double dy = b->y - b->y;
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return sqrt(dx*dx + dy*dy);
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}
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/*
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* Returns a link between two points
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*/
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Link* link_points(Point* a, Point* b){
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Link *output = malloc(sizeof(Link));
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output->a = a;
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output->b = b;
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output->length = distance(a, b);
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return output;
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}
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/*
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* Draws a line between linked points
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*/
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void draw_link(Canvas* c, Link* l){
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line(c, l->a->x, l->a->y, l->b->x, l->b->y);
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}
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/*
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* Updates the position of a point
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* the update is based on its position, its position in the previous frame (px, py)
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* and the forces acting upon it (fx,fy)
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*/
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void update_point(Point* p){
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uint tempx = p->x;
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uint tempy = p->y;
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p->x += (p->x - p->px) + p->fx;
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p->y += (p->y - p->py) + p->fy;
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p->px = tempx;
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p->py = tempy;
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}
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/* TODO
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* Moves points in link l such that their distance becomes l.length
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*/
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void update_link(Link* l){
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double cur_dist = distance(l->a->x, l->a->y, l->b->x, l->b->y);
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double delta = l->length - cur_dist;
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}
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