Quantize light frustum calculations (#12357)

* Quantize light frustum calculations

Reduces shadow flicker

* Fix function name to match conventions

diff --git a/src/client/shadows/dynamicshadows.cpp b/src/client/shadows/dynamicshadows.cpp
index ca2d3ce379954e6d0dce6f96629c838fbcd8e26c..9f26ba94ab8f673227def3d7520c87300071ba16 100644 (file)
--- a/src/client/shadows/dynamicshadows.cpp
+++ b/src/client/shadows/dynamicshadows.cpp
@@ -27,10 +27,24 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 using m4f = core::matrix4;
 
+static v3f quantizeDirection(v3f direction, float step)
+{
+
+       float yaw = std::atan2(direction.Z, direction.X);
+       float pitch = std::asin(direction.Y); // assume look is normalized
+
+       yaw = std::floor(yaw / step) * step;
+       pitch = std::floor(pitch / step) * step;
+
+       return v3f(std::cos(yaw)*std::cos(pitch), std::sin(pitch), std::sin(yaw)*std::cos(pitch));
+}
+
 void DirectionalLight::createSplitMatrices(const Camera *cam)
 {
+       const float DISTANCE_STEP = BS * 2.0; // 2 meters
        v3f newCenter;
        v3f look = cam->getDirection();
+       look = quantizeDirection(look, M_PI / 12.0); // 15 degrees
 
        // camera view tangents
        float tanFovY = tanf(cam->getFovY() * 0.5f);
@@ -42,6 +56,10 @@ void DirectionalLight::createSplitMatrices(const Camera *cam)
 
        // adjusted camera positions
        v3f cam_pos_world = cam->getPosition();
+       cam_pos_world = v3f(
+                       floor(cam_pos_world.X / DISTANCE_STEP) * DISTANCE_STEP,
+                       floor(cam_pos_world.Y / DISTANCE_STEP) * DISTANCE_STEP,
+                       floor(cam_pos_world.Z / DISTANCE_STEP) * DISTANCE_STEP);
        v3f cam_pos_scene = v3f(cam_pos_world.X - cam->getOffset().X * BS,
                        cam_pos_world.Y - cam->getOffset().Y * BS,
                        cam_pos_world.Z - cam->getOffset().Z * BS);
@@ -61,7 +79,7 @@ void DirectionalLight::createSplitMatrices(const Camera *cam)
        v3f boundVec = (cam_pos_scene + farCorner * sfFar) - center_scene;
        float radius = boundVec.getLength();
        float length = radius * 3.0f;
-       v3f eye_displacement = direction * length;
+       v3f eye_displacement = quantizeDirection(direction, M_PI / 2880 /*15 seconds*/) * length;
 
        // we must compute the viewmat with the position - the camera offset
        // but the future_frustum position must be the actual world position