物理引擎系统-ode

目录

物理引擎系统-ode

一、物理引擎系统-ode——processIslands

二、物理引擎系统-ode——processIslands

三、物理引擎系统-ode——processIslands

四、物理引擎系统-ode——processIslands

五、物理引擎系统-ode——processIslands

一、物理引擎系统-ode——processIslands 

static void processIslands (dxWorld *world, dReal stepsize)
{
  dxBody *b,*bb,**body;
  dxJoint *j,**joint;

  // nothing to do if no bodies
  if (world->nb <= 0) return;

二、物理引擎系统-ode——processIslands 

  // make arrays for body and joint lists (for a single island) to go into
  body = (dxBody**) ALLOCA (world->nb * sizeof(dxBody*));
  joint = (dxJoint**) ALLOCA (world->nj * sizeof(dxJoint*));
  int bcount = 0;    // number of bodies in `body'
  int jcount = 0;    // number of joints in `joint'

三、物理引擎系统-ode——processIslands 

  // set all body/joint tags to 0
  for (b=world->firstbody; b; b=(dxBody*)b->next) b->tag = 0;
  for (j=world->firstjoint; j; j=(dxJoint*)j->next) j->tag = 0;

  // allocate a stack of unvisited bodies in the island. the maximum size of
  // the stack can be the lesser of the number of bodies or joints, because
  // new bodies are only ever added to the stack by going through untagged
  // joints. all the bodies in the stack must be tagged!
  int stackalloc = (world->nj < world->nb) ? world->nj : world->nb;
  dxBody **stack = (dxBody**) ALLOCA (stackalloc * sizeof(dxBody*));

四、物理引擎系统-ode——processIslands 

  for (bb=world->firstbody; bb; bb=(dxBody*)bb->next) {
    // get bb = the next enabled, untagged body, and tag it
    if (bb->tag || (bb->flags & dxBodyDisabled)) continue;
    bb->tag = 1;

// tag all bodies and joints starting from bb.
    int stacksize = 0;
    b = bb;
    body[0] = bb;
    bcount = 1;
    jcount = 0;
    goto quickstart;
    while (stacksize > 0) {
      b = stack[--stacksize];    // pop body off stack
      body[bcount++] = b;    // put body on body list
      quickstart:

五、物理引擎系统-ode——processIslands 

      // traverse and tag all body's joints, add untagged connected bodies
      // to stack
      for (dxJointNode *n=b->firstjoint; n; n=n->next) {
    if (!n->joint->tag) {
      n->joint->tag = 1;
      joint[jcount++] = n->joint;
      if (n->body && !n->body->tag) {
        n->body->tag = 1;
        stack[stacksize++] = n->body;
      }
    }
      }
      dIASSERT(stacksize <= world->nb);
      dIASSERT(stacksize <= world->nj);
    }