soft shadow, shadow blur in SceneKit

Question

I add one node and try to setting shadow blur with SceneKit

here's my light config, I did try to set shadowRadius

light = [SCNLight light];
light.type = SCNLightTypeDirectional;
light.castsShadow = true;
light.shadowMode = SCNShadowModeForward;
light.shadowRadius = 5;
light.shadowMapSize=CGSizeMake(4000, 4000);
light.orthographicScale=25;
light.zNear=1;
light.zFar=1000;

but the result is not softer than when I not set shadowRadius it' here:

I did try to add samplecount

light = [SCNLight light];
light.type = SCNLightTypeDirectional;
light.castsShadow = true;
light.shadowMode = SCNShadowModeForward;
light.shadowRadius = 5;
// add samplecount
light.shadowSampleCount = 5;
light.shadowMapSize=CGSizeMake(4000, 4000);
light.orthographicScale=25;
light.zNear=1;
light.zFar=1000;

result look like following

shadow seem soft but this shadow start from bottom of the node (z coordinate is 0). I spend a lot of time to set soft shadow only in the edge of node, not from bottom. But no result.

This problem also occurred when add two node cross over(not only node and geometry as SCNFloor)

My problem is how to get shadow blur(soft shadow) with direction light.

any help would be appreciated!

From docs.microsoft.com/en-us/windows/win32/dxtecharts/…, I'm guessing the problem you're seeing might be so-called "peter panning"? I wish Apple would provide better conceptual and programming guide type content for SceneKit. Today, the automaticallyAdjustsShadowProjection property mentioned below is still not even documented. — StephenT

drewster drewster · Accepted Answer · 2018-02-14T13:14:02

Swift 4 / Xcode 9.2

I got a pretty good result with these settings:

light2.castsShadow = true
light2.automaticallyAdjustsShadowProjection = true
light2.maximumShadowDistance = 20.0
light2.orthographicScale = 1

light2.shadowMapSize = CGSize(width: 2048, height: 2048)
light2.shadowMode = .forward
light2.shadowSampleCount = 128
light2.shadowRadius = 3
light2.shadowBias  = 32

Increasing the shadowRadius to 12 helped a lot with my model, but then I needed to increase shadowSampleCount and shadowBias to not get artifacts.

soft shadow, shadow blur in SceneKit

2 Answers