From 5be3a4ce48b376600bed651ef27cbe2a952a2eae Mon Sep 17 00:00:00 2001
From: Ole Morud <olekr99@hotmail.com>
Date: Tue, 7 Jun 2022 15:28:29 +0200
Subject: [PATCH] gravity constant and gravitational acceleration

---
 physics.c | 44 ++++++++++++++++++++++++++------------------
 1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/physics.c b/physics.c
index 0bc8afc..5336df2 100644
--- a/physics.c
+++ b/physics.c
@@ -4,13 +4,16 @@
 #include <stdlib.h>
 #include <string.h>
 
+#define GRAVITY 0.01f
+#define FRAMERATE 10
+
 typedef struct Point{
-	uint x;
-	uint y;
-	uint px;
-	uint py;
-	uint fx;
-	uint fy;
+	double x;
+	double y;
+	double px;
+	double py;
+	double fx;
+	double fy;
 } Point;
 
 typedef struct Link {
@@ -22,14 +25,14 @@ typedef struct Link {
 
 
 void draw_link(Canvas* c, Link* l){
-	line(&c, l->a->x, l->a->y, l->b->x, l->b->y);
+	line(c, l->a->x, l->a->y, l->b->x, l->b->y);
 }
 
 void update_point(Point* p){
 	uint tempx = p->x;
 	uint tempy = p->y;
-	p->x += (p->x - p->px) + fx;
-	p->y += (p->y - p->py) + fy;
+	p->x += (p->x - p->px) + p->fx;
+	p->y += (p->y - p->py) + p->fy;
 	p->px = tempx;
 	p->py = tempy;
 }
@@ -38,25 +41,30 @@ void update_point(Point* p){
 int main(){
 	char *data = malloc(40*40);
 	Canvas c = {40, 40, data};
-	memset(c.data, '.', c.x * c.y);
 
+	Point a = { 10.0, 10.0,
+				10.0, 10.0, 
+				0.0, GRAVITY/FRAMERATE};
+
+	Point b = { 20.0, 10.0,
+				20.0, 10.0,
+				0.0, GRAVITY/FRAMERATE};
 
-	Point a = {10, 10, 10, 10, 0, 5};
-	Point b = {20, 10, 10, 10, 0, 5};
 	Link l_ab = {&a, &b, 10};
-
-	//line(&c, 1, 1, 8, 8);
-	//line(&c, 8, 8, 1, 1);
-	//line(&c, 0, 5, 8, 8);
 	
-	for(int i=0; i<100; i++){
+	while(1){
+		// clear canvas, calculate next frame and draw
+		memset(c.data, '.', c.x * c.y);
 		draw_link(&c, &l_ab);
 		update_point(&a);
 		update_point(&b);
+
+		// then render and wait
+		render(&c);
+		usleep(1000000/FRAMERATE);
 	}
 
 
-	render(&c);
 
 	return 0;
 }