Resolve Self-Collision Issues and Revise the 'Welcome' Example Scene #39

Job	Run time
build (linux, single, x86_64, template_debug, ubuntu-20.04)	1m 11s
build (windows, single, x86_32, template_debug, windows-latest)	4m 28s
build (windows, single, x86_64, template_debug, windows-latest)	3m 39s
build (macos, single, universal, template_debug, macos-latest)	1m 25s
build (android, single, arm64, template_debug, ubuntu-20.04)	1m 48s
build (android, single, arm32, template_debug, ubuntu-20.04)	2m 2s
build (android, single, x86_64, template_debug, ubuntu-20.04)	2m 56s
build (android, single, x86_32, template_debug, ubuntu-20.04)	3m 28s
build (ios, single, arm64, template_debug, macos-latest)	1m 12s
build (web, single, wasm32, template_debug, ubuntu-20.04)	1m 21s
build (linux, single, x86_64, template_release, ubuntu-20.04)	1m 12s
build (linux, double, x86_64, template_debug, ubuntu-20.04)	1m 15s
build (windows, double, x86_32, template_debug, windows-latest)	4m 12s
build (windows, double, x86_64, template_debug, windows-latest)	5m 24s
build (macos, double, universal, template_debug, macos-latest)	1m 29s
build (android, double, arm64, template_debug, ubuntu-20.04)	1m 55s
build (android, double, arm32, template_debug, ubuntu-20.04)	2m 32s
build (android, double, x86_64, template_debug, ubuntu-20.04)	1m 46s
build (android, double, x86_32, template_debug, ubuntu-20.04)	1m 54s
build (ios, double, arm64, template_debug, macos-latest)	1m 23s
build (web, double, wasm32, template_debug, ubuntu-20.04)	1m 20s
build (linux, double, x86_64, template_release, ubuntu-20.04)	1m 33s
merge	7s
package	11s
	49m 43s

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