private void SnapshotCollision()
{
Profiler.BeginSample("Snapshot");
numCollisions = 0;
// Loop through each node and get collisions within a radius.
for (int i = 0; i < nodes.Length; i++)
{
int collisions =
Physics2D.OverlapCircleNonAlloc(nodes[i].position, collisionRadius, colliderBuffer);
for (int j = 0; j < collisions; j++)
{
Collider2D col = colliderBuffer[j];
int id = col.GetInstanceID();
int idx = -1;
for (int k = 0; k < numCollisions; k++)
{
if (collisionInfos[k].id == id)
{
idx = k;
break;
}
}
// If we didn't have the collider, we need to add it.
if (idx < 0)
{
// Record all the data we need to use into our classes.
CollisionInfo ci = collisionInfos[numCollisions];
ci.id = id;
ci.wtl = col.transform.worldToLocalMatrix;
ci.ltw = col.transform.localToWorldMatrix;
ci.scale.x = ci.ltw.GetColumn(0).magnitude;
ci.scale.y = ci.ltw.GetColumn(1).magnitude;
ci.position = col.transform.position;
ci.numCollisions = 1; // 1 collision, this one.
ci.collidingNodes[0] = i;
switch (col)
{
case CircleCollider2D c:
ci.colliderType = ColliderType.Circle;
ci.colliderSize.x = ci.colliderSize.y = c.radius;
break;
case BoxCollider2D b:
ci.colliderType = ColliderType.Box;
ci.colliderSize = b.size;
break;
default:
ci.colliderType = ColliderType.None;
break;
}
numCollisions++;
if (numCollisions >= MAX_ROPE_COLLISIONS)
{
Profiler.EndSample();
return;
}
// If we found the collider, then we just have to increment the collisions and add our node.
}
else
{
CollisionInfo ci = collisionInfos[idx];
if (ci.numCollisions >= totalNodes)
{
continue;
}
ci.collidingNodes[ci.numCollisions++] = i;
}
}
}
shouldSnapshotCollision = false;
Profiler.EndSample();
}
private void Awake()
{
if (totalNodes > MAX_RENDER_POINTS)
{
Debug.LogError("Total nodes is more than MAX_RENDER_POINTS, so won't be able to render the entire rope.");
}
nodes = new VerletNode[totalNodes];
collisionInfos = new CollisionInfo[MAX_ROPE_COLLISIONS];
for (int i = 0; i < collisionInfos.Length; i++)
{
collisionInfos[i] = new CollisionInfo(totalNodes);
}
// Buffer for OverlapCircleNonAlloc.
colliderBuffer = new Collider2D[COLLIDER_BUFFER_SIZE];
renderPositions = new Vector4[totalNodes];
// Spawn nodes starting from the transform position and working down.
Vector2 pos = transform.position;
for (int i = 0; i < totalNodes; i++)
{
nodes[i] = new VerletNode(pos);
renderPositions[i] = new Vector4(pos.x, pos.y, 1, 1);
pos.y -= nodeDistance;
}
// Mesh setup.
Mesh mesh = new Mesh();
{
Vector3[] vertices = new Vector3[totalNodes * VERTICES_PER_NODE];
int[] triangles = new int[totalNodes * TRIANGLES_PER_NODE * 3];
for (int i = 0; i < totalNodes; i++)
{
// 4 triangles per node, 3 indices per triangle.
int idx = i * TRIANGLES_PER_NODE * 3;
// 8 vertices per node.
int vIdx = i * VERTICES_PER_NODE;
// Unity uses a CLOCKWISE WINDING ORDER -- clockwise tri indices are facing the camera.
triangles[idx + 0] = vIdx; // v1 top
triangles[idx + 1] = vIdx + 1; // v2 bottom
triangles[idx + 2] = vIdx + 2; // v1 bottom
triangles[idx + 3] = vIdx; // v1 top
triangles[idx + 4] = vIdx + 3; // v2 top
triangles[idx + 5] = vIdx + 1; // v2 bottom
triangles[idx + 6] = vIdx + 4; // tl
triangles[idx + 7] = vIdx + 7; // br
triangles[idx + 8] = vIdx + 6; // bl
triangles[idx + 9] = vIdx + 4; // tl
triangles[idx + 10] = vIdx + 5; // tr
triangles[idx + 11] = vIdx + 7; // br
}
// We only really care about the number of vertices, not what they actually are -- the positions aren't used.
mesh.vertices = vertices;
mesh.triangles = triangles;
// Since we pretty much want the rope to always render (it's always going to be on screen if it's active), we
// just set the bounds super large to avoid recalculating the bounds when the rope changes.
mesh.bounds = new Bounds(Vector3.zero, Vector3.one * 100f);
}
GetComponent <MeshFilter>().mesh = mesh;
material = GetComponent <MeshRenderer>().material;
material.SetFloat("_Width", drawWidth);
}
private void AdjustCollisions()
{
Profiler.BeginSample("Collision");
for (int i = 0; i < numCollisions; i++)
{
CollisionInfo ci = collisionInfos[i];
switch (ci.colliderType)
{
case ColliderType.Circle: {
float radius = ci.colliderSize.x * Mathf.Max(ci.scale.x, ci.scale.y);
for (int j = 0; j < ci.numCollisions; j++)
{
VerletNode node = nodes[ci.collidingNodes[j]];
float distance = Vector2.Distance(ci.position, node.position);
// Early out if we're not colliding.
if (distance - radius > 0)
{
continue;
}
Vector2 dir = (node.position - ci.position).normalized;
Vector2 hitPos = ci.position + dir * radius;
node.position = hitPos;
}
}
break;
case ColliderType.Box: {
for (int j = 0; j < ci.numCollisions; j++)
{
VerletNode node = nodes[ci.collidingNodes[j]];
Vector2 localPoint = ci.wtl.MultiplyPoint(node.position);
// If distance from center is more than box "radius", then we can't be colliding.
Vector2 half = ci.colliderSize * .5f;
Vector2 scalar = ci.scale;
float dx = localPoint.x;
float px = half.x - Mathf.Abs(dx);
if (px <= 0)
{
continue;
}
float dy = localPoint.y;
float py = half.x - Mathf.Abs(dy);
if (py <= 0)
{
continue;
}
// Need to multiply distance by scale or we'll mess up on scaled box corners.
if (px * scalar.x < py * scalar.y)
{
float sx = Mathf.Sign(dx);
localPoint.x = half.x * sx;
}
else
{
float sy = Mathf.Sign(dy);
localPoint.y = half.y * sy;
}
Vector2 hitPos = ci.ltw.MultiplyPoint(localPoint);
node.position = hitPos;
}
}
break;
}
}
Profiler.EndSample();
}