public virtual void ApplyTraction()
{
if (kineticEnergies.horizontal.X == Fix.Zero)
{
return;
}
bool startedDir = FixMath.Sign(kineticEnergies.horizontal.X) == 1 ? true : false;
if (startedDir)
{
kineticEnergies.horizontal._x -= cInfo.attributes.traction;
if (kineticEnergies.horizontal.X < Fix.Zero)
{
kineticEnergies.horizontal = FixVec2.Zero;
}
}
else
{
kineticEnergies.horizontal._x += cInfo.attributes.traction;
if (kineticEnergies.horizontal.X > Fix.Zero)
{
kineticEnergies.horizontal = FixVec2.Zero;
}
}
}
// The smaller of the two possible angles between the two vectors is returned, therefore the result will never be greater than 180 degrees or smaller than -180 degrees.
// If you imagine the from and to vectors as lines on a piece of paper, both originating from the same point, then the /axis/ vector would point up out of the paper.
// The measured angle between the two vectors would be positive in a clockwise direction and negative in an anti-clockwise direction.
public static Fix64 SignedAngle(FixVector3 from, FixVector3 to, FixVector3 axis)
{
FixVector3 fromNorm = from.Normalized, toNorm = to.Normalized;
Fix64 unsignedAngle = FixMath.Acos(FixMath.Clamp(Dot(fromNorm, toNorm), -Fix64.ONE, Fix64.ONE)) * FixMath.Rad2Deg;
Fix64 sign = FixMath.Sign(Dot(axis, Cross(fromNorm, toNorm)));
return(unsignedAngle * sign);
}
/// <summary>
/// checks the center point under the BoxCollider2D for a slope. If it finds one then the deltaMovement is adjusted so that
/// the player stays grounded and the slopeSpeedModifier is taken into account to speed up movement.
/// </summary>
/// <param name="deltaMovement">Delta movement.</param>
private void handleVerticalSlope(ref FixVec2 deltaMovement)
{
// slope check from the center of our collider
Fix centerOfCollider = (_raycastOrigins.bottomLeft.x + _raycastOrigins.bottomRight.x) * (Fix.one / 2);
FixVec2 rayDirection = -FixVec2.up;
// the ray distance is based on our slopeLimit
Fix slopeCheckRayDistance = _slopeLimitTangent * (_raycastOrigins.bottomRight.x - centerOfCollider);
FixVec2 slopeRay = new FixVec2(centerOfCollider, _raycastOrigins.bottomLeft.y);
_raycastHit = TFPhysics.Raycast(slopeRay, rayDirection, slopeCheckRayDistance, platformMask);
if (_raycastHit)
{
// bail out if we have no slope
var angle = FixVec2.Angle(_raycastHit.normal, FixVec2.up);
if (angle == 0)
{
return;
}
// we are moving down the slope if our normal and movement direction are in the same x direction
var isMovingDownSlope = FixMath.Sign(_raycastHit.normal.x) == FixMath.Sign(deltaMovement.x);
if (isMovingDownSlope)
{
// going down we want to speed up in most cases so the slopeSpeedMultiplier curve should be > 1 for negative angles
Fix slopeModifier = (Fix)slopeSpeedMultiplier.Evaluate((float)-angle);
// we add the extra downward movement here to ensure we "stick" to the surface below
deltaMovement.y += _raycastHit.point.y - slopeRay.y - skinWidth;
deltaMovement = new FixVec2(deltaMovement.x, deltaMovement.y)
+ new FixVec2(deltaMovement.x * slopeModifier * (1 - (angle / 90)), (deltaMovement.x * slopeModifier * (angle / 90)));
collisionState.movingDownSlope = true;
collisionState.slopeAngle = angle;
}
}
}
/// <summary>
/// we have to use a bit of trickery in this one. The rays must be cast from a small distance inside of our
/// collider (skinWidth) to avoid zero distance rays which will get the wrong normal. Because of this small offset
/// we have to increase the ray distance skinWidth then remember to remove skinWidth from deltaMovement before
/// actually moving the player
/// </summary>
void moveHorizontally(ref FixVec2 deltaMovement)
{
var isGoingRight = deltaMovement.x > 0;
var rayDistance = FixMath.Abs(deltaMovement.x) + _skinWidth;
var rayDirection = isGoingRight ? FixVec2.right : -FixVec2.right;
var initialRayOrigin = isGoingRight ? _raycastOrigins.bottomRight : _raycastOrigins.bottomLeft;
for (var i = 0; i < totalHorizontalRays; i++)
{
var ray = new FixVec2(initialRayOrigin.x, initialRayOrigin.y + i * _verticalDistanceBetweenRays);
// if we are grounded we will include oneWayPlatforms only on the first ray (the bottom one). this will allow us to
// walk up sloped oneWayPlatforms.
if (i == 0 && collisionState.wasGroundedLastFrame)
{
_raycastHit = TFPhysics.Raycast(ray, rayDirection, rayDistance, platformMask);
}
else
{
_raycastHit = TFPhysics.Raycast(ray, rayDirection, rayDistance, platformMask & ~oneWayPlatformMask);
}
if (_raycastHit)
{
// the bottom ray can hit a slope but no other ray can so we have special handling for these cases
if (i == 0 && handleHorizontalSlope(ref deltaMovement, FixVec2.Angle(_raycastHit.normal, FixVec2.up)))
{
_raycastHitsThisFrame.Add(_raycastHit);
// if we weren't grounded last frame, that means we're landing on a slope horizontally.
// this ensures that we stay flush to that slope
if (!collisionState.wasGroundedLastFrame)
{
Fix flushDistance = FixMath.Sign(deltaMovement.x) * (_raycastHit.distance - skinWidth);
tfTransform.Position += new FixVec2(flushDistance, 0);
}
break;
}
// set our new deltaMovement and recalculate the rayDistance taking it into account
deltaMovement.x = _raycastHit.point.x - ray.x;
rayDistance = FixMath.Abs(deltaMovement.x);
// remember to remove the skinWidth from our deltaMovement
if (isGoingRight)
{
deltaMovement.x -= _skinWidth;
collisionState.right = true;
}
else
{
deltaMovement.x += _skinWidth;
collisionState.left = true;
}
_raycastHitsThisFrame.Add(_raycastHit);
// we add a small fudge factor for the float operations here. if our rayDistance is smaller
// than the width + fudge bail out because we have a direct impact
if (rayDistance < _skinWidth + kSkinWidthFloatFudgeFactor)
{
break;
}
}
}
}