/// <summary>
/// Nudge the tree to create a zig-zag effect (so that the tree isn't dead straight)
/// </summary>
/// <param name="trunk">A trunk particle</param>
private void TrunkNudgeBehaviour(Particle2D trunk)
{
// subtle x nudgings
if (rnd.NextDouble() < zigzagTrunkPercentage)
{
// rotate the growing vector by a random zigzag strength factor
trunk.Direction = trunk.Direction.Rotate(LineairScaleTo(rnd.NextDouble(), -zigzagTrunkStrength, zigzagTrunkStrength));
}
if (trunk.Direction.Y < 1)
{
trunk.Direction.Y += 0.1f;
}
if (trunk.Direction.Y > 1)
{
trunk.Direction.Y = 1;
}
}
/// <summary>
/// Describes the branching and general behaviour of a branch
/// </summary>
/// <param name="branchingPercent"></param>
/// <param name="branch"></param>
/// <param name="depth"></param>
private void BranchingBehaviour(float branchingPercent, Particle2D t, int depth)
{
if (rnd.NextDouble() < branchingPercent)//* (Math.Pow(0.5f, depth)))
{
// 90 * 2 ^ depth-1
// [-90, 90] degrees => depth =1
// [-45, 45] degrees => depth = 2
// [-22.5,
double narrower = (Math.Pow(branchNarrowing, depth));
// create a branch
Vector2D initialDirection = t.Direction.Rotate(rnd.Next(-Math.PI * narrower, Math.PI * narrower));
Particle2D branch = new Particle2D()
{
Location = t.Location,
Direction = initialDirection,
// the life is based on the the life where it's splitting from (branch or trunk) but reduce the life of the new branch by a factor
MaxLife = (int)(t.Life * branchSizeDecrease),
Life = (int)(t.Life * branchSizeDecrease),
Color = branchColor,
};
// define the behaviour of the branch
branch.Behaviour = b =>
{
// branches should sprout leaves
LeavesBehaviour(b);
// branches can branch again
BranchingBehaviour(branchingPercent, b, depth + 1);
// weight behaviour
if (applyWeightOnBranches)
{
b.Direction = new Vector2D(initialDirection.X, initialDirection.Y * LineairScaleTo((double)b.Life / (double)branch.MaxLife, -1f, 1f)); // +(2 * (((double)b.Life / (double)maxLife)) - 1);
}
};
particles.Add(branch);
}
}
/// <summary>
/// Describes the behaviour of spawning leaves on branches
/// </summary>
/// <param name="b"></param>
private void LeavesBehaviour(Particle2D b)
{
// if the branch doesn't have a lot of life left (based on the leaves percentage)
if (b.Life < leavesPercentage * b.MaxLife)
{
// create leaf particles
for (int i = 0; i < leavesNrSpawned; i++)
{
// leaves have no particular behaviour, they just grow until its life is done
Particle2D l = new Particle2D()
{
Direction = new Vector2D(rnd.Next(-1f, 1f), rnd.Next(-1f, 1f)),
Location = b.Location,
Color = leavesColor,
Life = leafLife,
MaxLife = leafLife
};
particles.Add(l);
}
}
}
/// <summary>
/// Describes how a trunk splits
/// </summary>
/// <param name="trunk">The trunk particle</param>
private void TrunkSplittingBehaviour(Particle2D trunk)
{
// trunk split
if (rnd.NextDouble() < trunkSplitPercentage)
{
// spawn a branch of the trunk in a direction random between [-pi, pi]
Vector2D newDirection = trunk.Direction.Rotate(rnd.Next(-Math.PI, Math.PI));
Particle2D secondTrunk = new Particle2D()
{
Location = trunk.Location,
Direction = newDirection,
Color = trunk.Color,
// reduce its max life with the specified decrease
Life = (int)(trunk.Life * trunkSplitSpawnLifeDecrease),
MaxLife = (int)(trunk.Life * trunkSplitSpawnLifeDecrease),
Behaviour = trunk.Behaviour
};
particles.Add(secondTrunk);
// if the trhunk if going down, flip it (trunks don't grow down)
if (secondTrunk.Direction.Y < 0)
{
secondTrunk.Direction.Y *= -1;
}
// reduce the original trunk's life (because splitting has a cost)
trunk.Life = (int)(trunk.Life * trunkSplitOrigLifeDecrease);
// mirror the new trunk direction to give to the original trunk
trunk.Direction = new Vector2D(-newDirection.X, newDirection.Y); //trunk.Direction.Rotate(-Math.PI / 2 * rnd.NextDouble());
// again, check if it's going down and if so flip it
if (trunk.Direction.Y < 0)
{
trunk.Direction.Y *= -1;
}
}
}
