X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=dosdemo;a=blobdiff_plain;f=tools%2Fropesim%2Fsrc%2Fropesim.c;h=869d4e9caed09b83df4c874233b57d34871cf9d1;hp=12c70c437931e7cb3bfcf2c8f933dad2e98d40e4;hb=2ee531a10bad1036d2279f9b626da72e345a3b37;hpb=1ae209a77434dcdf7266d2cf95d3f20c0de7a0e9

diff --git a/tools/ropesim/src/ropesim.c b/tools/ropesim/src/ropesim.c
index 12c70c4..869d4e9 100644
--- a/tools/ropesim/src/ropesim.c
+++ b/tools/ropesim/src/ropesim.c
@@ -35,15 +35,11 @@ static void step(struct rsim_world *rsim, struct rsim_rope *rope, float dt)
 {
 	int i;
 	float len, fmag;
-	cgm_vec3 npos, force, dir;
+	cgm_vec3 npos, faccel, dir;
 	float inv_damp = rsim->damping == 0.0f ? 1.0f : (1.0f - rsim->damping);
 	struct rsim_mass *mass = rope->masses;
 	struct rsim_spring *spr = rope->springs;
 
-	force.x = rsim->grav.x + rsim->extforce.x;
-	force.y = rsim->grav.y + rsim->extforce.y;
-	force.z = rsim->grav.z + rsim->extforce.z;
-
 	/* accumulate forces from springs */
 	for(i=0; i<rope->num_springs; i++) {
 		dir = spr->mass[1]->p;
@@ -58,9 +54,13 @@ static void step(struct rsim_world *rsim, struct rsim_rope *rope, float dt)
 		}
 		fmag = (len - spr->rest_len) * spr->k;
 
-		cgm_vscale(&dir, fmag);
-		cgm_vadd(&spr->mass[0]->f, &dir);
-		cgm_vsub(&spr->mass[1]->f, &dir);
+		spr->mass[0]->f.x += dir.x * fmag / spr->mass[0]->m;
+		spr->mass[0]->f.y += dir.y * fmag / spr->mass[0]->m;
+		spr->mass[0]->f.z += dir.z * fmag / spr->mass[0]->m;
+
+		spr->mass[1]->f.x -= dir.x * fmag / spr->mass[1]->m;
+		spr->mass[1]->f.y -= dir.y * fmag / spr->mass[1]->m;
+		spr->mass[1]->f.z -= dir.z * fmag / spr->mass[1]->m;
 
 		spr++;
 	}
@@ -73,7 +73,11 @@ static void step(struct rsim_world *rsim, struct rsim_rope *rope, float dt)
 		}
 
 		/* add constant forces to accumulated mass force */
-		cgm_vadd(&mass->f, &force);
+		cgm_vadd(&mass->f, &rsim->grav);
+
+		faccel = rsim->extforce;
+		cgm_vscale(&faccel, 1.0f / mass->m);
+		cgm_vadd(&mass->f, &rsim->extforce);
 
 		mass->v.x = (mass->v.x - mass->v.x * inv_damp * dt) + mass->f.x * dt;
 		mass->v.y = (mass->v.y - mass->v.y * inv_damp * dt) + mass->f.y * dt;