public int Compare(FogNode x, FogNode y)
{
if (x.Priority < y.Priority)
{
return(+1);
}
if (x.Priority > y.Priority)
{
return(-1);
}
return(y.SortTag.CompareTo(x.SortTag));
}
// OnLoad() is called when the GameObject is added to the IGameObjectService.
protected override void OnLoad()
{
FogNode = new FogNode(new Fog())
{
IsEnabled = false,
Name = "Fog",
};
AddFogNodeToScene();
// Add GUI controls to the Options window.
var sampleFramework = _services.GetInstance<SampleFramework>();
var optionsPanel = sampleFramework.AddOptions("Game Objects");
var panel = SampleHelper.AddGroupBox(optionsPanel, "FogObject");
SampleHelper.AddCheckBox(
panel,
"Enable fog",
FogNode.IsEnabled,
isChecked => FogNode.IsEnabled = isChecked);
SampleHelper.AddCheckBox(
panel,
"Attach to camera",
AttachToCamera,
isChecked => AttachToCamera = isChecked);
SampleHelper.AddSlider(
panel,
"Fog ramp start",
"F2",
0,
1000,
FogNode.Fog.Start,
value => FogNode.Fog.Start = value);
SampleHelper.AddSlider(
panel,
"Fog ramp end",
"F2",
0,
5000,
FogNode.Fog.End,
value => FogNode.Fog.End = value);
SampleHelper.AddSlider(
panel,
"Density",
"F2",
0.0f,
2,
FogNode.Fog.Density,
value => FogNode.Fog.Density = value);
SampleHelper.AddSlider(
panel,
"Height falloff",
"F2",
-1,
1,
FogNode.Fog.HeightFalloff,
value => FogNode.Fog.HeightFalloff = value);
SampleHelper.AddSlider(
panel,
"Height Y",
"F2",
-100,
100,
FogNode.PoseWorld.Position.Y,
value =>
{
var pose = FogNode.PoseWorld;
pose.Position.Y = value;
FogNode.PoseWorld = pose;
});
}
/// <summary>
/// Called to compute the fog intensity for <see cref="GetIntensity"/>.
/// </summary>
/// <param name="fogNode">The fog node. (Is never <see langword="null"/>.)</param>
/// <param name="cameraNode">The camera node. (Is never <see langword="null"/>.)</param>
/// <param name="targetPosition">The target position.</param>
/// <returns>The fog intensity (0 = no fog; 1 = full fog, nothing else visible).</returns>
/*protected virtual*/
private float OnGetIntensity(FogNode fogNode, CameraNode cameraNode, Vector3F targetPosition)
{
// These computations are the same as in FogRenderer and the Fog shader files.
if (Numeric.IsZero(Density))
return 0;
Vector3F cameraToPosition = targetPosition - cameraNode.PoseWorld.Position;
float distance = cameraToPosition.Length; // The distance traveled inside the fog.
Vector3F cameraToPositionDirection = cameraToPosition / distance;
// Compute a value that is 0 at Start and 1 at End.
float ramp = (distance - Start) / (End - Start);
// Smoothstep distance fog
float smoothRamp = InterpolationHelper.HermiteSmoothStep(ramp);
// Exponential Fog
float referenceHeight = cameraNode.PoseWorld.Position.Y - fogNode.PoseWorld.Position.Y
+ cameraToPositionDirection.Y * Start;
float distanceInFog = distance - Start;
var fogDirection = cameraToPositionDirection;
if (HeightFalloff * fogDirection.Y < 0)
{
referenceHeight += fogDirection.Y * distanceInFog;
fogDirection = -fogDirection;
}
float referenceDensity = Density * (float)Math.Pow(2, -HeightFalloff * referenceHeight);
float opticalLength = GetOpticalLengthInHeightFog(distanceInFog, referenceDensity, fogDirection * distanceInFog, HeightFalloff);
float heightFog = (1 - (float)Math.Pow(2, -opticalLength * 1));
// Get alpha from BottomColor and TopColor.
// (Note: We have to avoid division by zero.)
float height = targetPosition.Y - fogNode.PoseWorld.Position.Y;
float p = MathHelper.Clamp((height - Height0) / Math.Max(Height1 - Height0, 0.0001f), 0, 1);
float alpha = InterpolationHelper.Lerp(Color0.W, Color1.W, p);
return smoothRamp * heightFog * alpha;
}
/// <summary>
/// Gets the fog intensity at the specified target position.
/// </summary>
/// <param name="fogNode">The fog node.</param>
/// <param name="cameraNode">The camera node.</param>
/// <param name="targetPosition">The target position.</param>
/// <returns>The fog intensity (0 = no fog; 1 = full fog, nothing else visible).</returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="fogNode"/> or <paramref name="cameraNode"/> is <see langword="null"/>.
/// </exception>
public float GetIntensity(FogNode fogNode, CameraNode cameraNode, Vector3F targetPosition)
{
if (fogNode == null)
throw new ArgumentNullException("fogNode");
if (cameraNode == null)
throw new ArgumentNullException("cameraNode");
return OnGetIntensity(fogNode, cameraNode, targetPosition);
}
