private Matrix4x4 UpdateDirectionalLightMatrices(
GraphicsDevice gd,
SceneContext sc,
float near,
float far,
uint shadowMapWidth,
out BoundingFrustum lightFrustum)
{
Vector3 lightDir = sc.DirectionalLight.Direction;
Vector3 viewDir = sc.Camera.LookDirection;
Vector3 viewPos = sc.Camera.Position;
Vector3 unitY = Vector3.UnitY;
FrustumCorners cameraCorners;
if (gd.IsDepthRangeZeroToOne)
{
FrustumHelpers.ComputePerspectiveFrustumCorners(
ref viewPos,
ref viewDir,
ref unitY,
sc.Camera.FieldOfView,
far,
near,
sc.Camera.AspectRatio,
out cameraCorners);
}
else
{
FrustumHelpers.ComputePerspectiveFrustumCorners(
ref viewPos,
ref viewDir,
ref unitY,
sc.Camera.FieldOfView,
near,
far,
sc.Camera.AspectRatio,
out cameraCorners);
}
// Approach used: http://alextardif.com/ShadowMapping.html
Vector3 frustumCenter = Vector3.Zero;
frustumCenter += cameraCorners.NearTopLeft;
frustumCenter += cameraCorners.NearTopRight;
frustumCenter += cameraCorners.NearBottomLeft;
frustumCenter += cameraCorners.NearBottomRight;
frustumCenter += cameraCorners.FarTopLeft;
frustumCenter += cameraCorners.FarTopRight;
frustumCenter += cameraCorners.FarBottomLeft;
frustumCenter += cameraCorners.FarBottomRight;
frustumCenter /= 8f;
float radius = (cameraCorners.NearTopLeft - cameraCorners.FarBottomRight).Length() / 2.0f;
float texelsPerUnit = shadowMapWidth / (radius * 2.0f);
Matrix4x4 scalar = Matrix4x4.CreateScale(texelsPerUnit, texelsPerUnit, texelsPerUnit);
Vector3 baseLookAt = -lightDir;
Matrix4x4 lookat = Matrix4x4.CreateLookAt(Vector3.Zero, baseLookAt, Vector3.UnitY);
lookat = scalar * lookat;
Matrix4x4.Invert(lookat, out Matrix4x4 lookatInv);
frustumCenter = Vector3.Transform(frustumCenter, lookat);
frustumCenter.X = (int)frustumCenter.X;
frustumCenter.Y = (int)frustumCenter.Y;
frustumCenter = Vector3.Transform(frustumCenter, lookatInv);
Vector3 lightPos = frustumCenter - (lightDir * radius * 2f);
Matrix4x4 lightView = Matrix4x4.CreateLookAt(lightPos, frustumCenter, Vector3.UnitY);
Matrix4x4 lightProjection = Util.CreateOrtho(
gd,
gd.IsDepthRangeZeroToOne,
-radius * _lScale,
radius * _rScale,
-radius * _bScale,
radius * _tScale,
-radius * _nScale,
radius * _fScale);
Matrix4x4 viewProjectionMatrix = lightView * lightProjection;
lightFrustum = new BoundingFrustum(viewProjectionMatrix);
return(viewProjectionMatrix);
}
private void UpdateLightProjection()
{
if (MainCamera == null)
{
return;
}
if (Light == null)
{
_lightProjectionProvider.Data = Matrix4x4.Identity;
_lightViewProvider.Data = Matrix4x4.Identity;
return;
}
Vector3 cameraDir = MainCamera.Transform.Forward;
Vector3 unitY = Vector3.UnitY;
Vector3 cameraPosition = MainCamera.Transform.Position;
FrustumCorners corners;
FrustumHelpers.ComputePerspectiveFrustumCorners(
ref cameraPosition,
ref cameraDir,
ref unitY,
MainCamera.FieldOfViewRadians,
MainCamera.NearPlaneDistance,
MainCamera.FarPlaneDistance,
(float)RenderContext.Window.Width / (float)RenderContext.Window.Height,
out corners);
// Approach used: http://alextardif.com/ShadowMapping.html
Vector3 frustumCenter = Vector3.Zero;
frustumCenter += corners.NearTopLeft;
frustumCenter += corners.NearTopRight;
frustumCenter += corners.NearBottomLeft;
frustumCenter += corners.NearBottomRight;
frustumCenter += corners.FarTopLeft;
frustumCenter += corners.FarTopRight;
frustumCenter += corners.FarBottomLeft;
frustumCenter += corners.FarBottomRight;
frustumCenter /= 8f;
float radius = (corners.NearTopLeft - corners.FarBottomRight).Length() / 2.0f;
float texelsPerUnit = (float)DepthMapWidth / (radius * 2.0f);
Matrix4x4 scalar = Matrix4x4.CreateScale(texelsPerUnit, texelsPerUnit, texelsPerUnit);
var _lightDirection = Light.Direction;
Vector3 baseLookAt = -_lightDirection;
Matrix4x4 lookat = Matrix4x4.CreateLookAt(Vector3.Zero, baseLookAt, Vector3.UnitY);
lookat = scalar * lookat;
Matrix4x4 lookatInv;
Matrix4x4.Invert(lookat, out lookatInv);
frustumCenter = Vector3.Transform(frustumCenter, lookat);
frustumCenter.X = (int)frustumCenter.X;
frustumCenter.Y = (int)frustumCenter.Y;
frustumCenter = Vector3.Transform(frustumCenter, lookatInv);
Vector3 lightPos = frustumCenter - (_lightDirection * radius * 2f);
Matrix4x4 lightView = Matrix4x4.CreateLookAt(lightPos, frustumCenter, Vector3.UnitY);
_lightProjectionProvider.Data = Matrix4x4.CreateOrthographicOffCenter(
-radius, radius, -radius, radius, -radius * 4f, radius * 4f);
_lightViewProvider.Data = lightView;
}