Game Engines 2021W Lecture 19 - Revision history

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	Godot's SDFGI & related tech		Godot's SDFGI & related tech
	* Juan Linietsky, [https://godotengine.org/article/godot-40-gets-sdf-based-real-time-global-illumination Godot 4.0 gets SDF-based real time global illumination]		* Juan Linietsky, [https://godotengine.org/article/godot-40-gets-sdf-based-real-time-global-illumination Godot 4.0 gets SDF-based real time global illumination] (2020)
	* Daniel Wright, [https://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf Dynamic Occlusion with Signed Distance Fields] (SIGGRAPH 2015)		* Daniel Wright, [https://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf Dynamic Occlusion with Signed Distance Fields] (SIGGRAPH 2015)
	* Jamie Wong, [http://jamie-wong.com/2016/07/15/ray-marching-signed-distance-functions/ Ray Marching and Signed Distance Functions]		* Jamie Wong, [http://jamie-wong.com/2016/07/15/ray-marching-signed-distance-functions/ Ray Marching and Signed Distance Functions] (2016)
	* Jinkai Hu et al, [https://deepai.org/publication/signed-distance-fields-dynamic-diffuse-global-illumination Signed Distance Fields Dynamic Diffuse Global Illumination]		* Jinkai Hu et al, [https://deepai.org/publication/signed-distance-fields-dynamic-diffuse-global-illumination Signed Distance Fields Dynamic Diffuse Global Illumination] (2020)

	==Notes==		==Notes==

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Resources

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	* Daniel Wright, [https://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf Dynamic Occlusion with Signed Distance Fields] (SIGGRAPH 2015)		* Daniel Wright, [https://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf Dynamic Occlusion with Signed Distance Fields] (SIGGRAPH 2015)
	* Jamie Wong, [http://jamie-wong.com/2016/07/15/ray-marching-signed-distance-functions/ Ray Marching and Signed Distance Functions]		* Jamie Wong, [http://jamie-wong.com/2016/07/15/ray-marching-signed-distance-functions/ Ray Marching and Signed Distance Functions]
	* https://deepai.org/publication/signed-distance-fields-dynamic-diffuse-global-illumination		* Jinkai Hu et al, [https://deepai.org/publication/signed-distance-fields-dynamic-diffuse-global-illumination Signed Distance Fields Dynamic Diffuse Global Illumination]

	==Notes==		==Notes==

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Resources

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	* [http://www.pbr-book.org/3ed-2018/Introduction/Photorealistic_Rendering_and_the_Ray-Tracing_Algorithm.html Photorealistic rendering and the ray tracing algorithm] from [http://www.pbr-book.org/3ed-2018/contents.html Physically Based Rendering: From Theory To Implementation] by Matt Pharr, Wenzel Jakob, and Greg Humphreys.		* [http://www.pbr-book.org/3ed-2018/Introduction/Photorealistic_Rendering_and_the_Ray-Tracing_Algorithm.html Photorealistic rendering and the ray tracing algorithm] from [http://www.pbr-book.org/3ed-2018/contents.html Physically Based Rendering: From Theory To Implementation] by Matt Pharr, Wenzel Jakob, and Greg Humphreys.

	Godot's SDFGI		Godot's SDFGI & related tech
	* Juan Linietsky, [https://godotengine.org/article/godot-40-gets-sdf-based-real-time-global-illumination Godot 4.0 gets SDF-based real time global illumination]		* Juan Linietsky, [https://godotengine.org/article/godot-40-gets-sdf-based-real-time-global-illumination Godot 4.0 gets SDF-based real time global illumination]
	* Daniel Wright, [https://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf Dynamic Occlusion with Signed Distance Fields] (SIGGRAPH 2015)		* Daniel Wright, [https://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf Dynamic Occlusion with Signed Distance Fields] (SIGGRAPH 2015)
	* http://jamie-wong.com/2016/07/15/ray-marching-signed-distance-functions/		* Jamie Wong, [http://jamie-wong.com/2016/07/15/ray-marching-signed-distance-functions/ Ray Marching and Signed Distance Functions]
	* https://deepai.org/publication/signed-distance-fields-dynamic-diffuse-global-illumination		* https://deepai.org/publication/signed-distance-fields-dynamic-diffuse-global-illumination

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Resources

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	Godot's SDFGI		Godot's SDFGI
	* Juan Linietsky, [https://godotengine.org/article/godot-40-gets-sdf-based-real-time-global-illumination Godot 4.0 gets SDF-based real time global illumination]		* Juan Linietsky, [https://godotengine.org/article/godot-40-gets-sdf-based-real-time-global-illumination Godot 4.0 gets SDF-based real time global illumination]
	* ~~http~~://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf		* Daniel Wright, [https://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf Dynamic Occlusion with Signed Distance Fields] (SIGGRAPH 2015)
	* http://jamie-wong.com/2016/07/15/ray-marching-signed-distance-functions/		* http://jamie-wong.com/2016/07/15/ray-marching-signed-distance-functions/
	* https://deepai.org/publication/signed-distance-fields-dynamic-diffuse-global-illumination		* https://deepai.org/publication/signed-distance-fields-dynamic-diffuse-global-illumination

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Resources

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	Godot's SDFGI		Godot's SDFGI
	* [https://godotengine.org/article/godot-40-gets-sdf-based-real-time-global-illumination Godot gets SDF-based real time global illumination]		* Juan Linietsky, [https://godotengine.org/article/godot-40-gets-sdf-based-real-time-global-illumination Godot 4.0 gets SDF-based real time global illumination]
	* http://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf		* http://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf
	* http://jamie-wong.com/2016/07/15/ray-marching-signed-distance-functions/		* http://jamie-wong.com/2016/07/15/ray-marching-signed-distance-functions/

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Resources

← Older revision		Revision as of 21:37, 23 March 2021
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	* [http://www.pbr-book.org/3ed-2018/Introduction/Photorealistic_Rendering_and_the_Ray-Tracing_Algorithm.html Photorealistic rendering and the ray tracing algorithm] from [http://www.pbr-book.org/3ed-2018/contents.html Physically Based Rendering: From Theory To Implementation] by Matt Pharr, Wenzel Jakob, and Greg Humphreys.		* [http://www.pbr-book.org/3ed-2018/Introduction/Photorealistic_Rendering_and_the_Ray-Tracing_Algorithm.html Photorealistic rendering and the ray tracing algorithm] from [http://www.pbr-book.org/3ed-2018/contents.html Physically Based Rendering: From Theory To Implementation] by Matt Pharr, Wenzel Jakob, and Greg Humphreys.

	Godot's ~~SPFGI~~		Godot's SDFGI
	* [https://godotengine.org/article/godot-40-gets-sdf-based-real-time-global-illumination Godot gets SDF-based real time global illumination]		* [https://godotengine.org/article/godot-40-gets-sdf-based-real-time-global-illumination Godot gets SDF-based real time global illumination]
	* http://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf		* http://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf

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Resources

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	==Resources==		==Resources==

			Ray tracing
	* Sarah Abraham's [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures.html Computer Graphics lecture notes], especially her notes on [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures/cs354-4.pdf basic ray tracing] and [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures/cs354-raytracing_pseudocode.pdf ray tracing pseudocode].		* Sarah Abraham's [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures.html Computer Graphics lecture notes], especially her notes on [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures/cs354-4.pdf basic ray tracing] and [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures/cs354-raytracing_pseudocode.pdf ray tracing pseudocode].
	* Scratapixel's [https://www.scratchapixel.com/lessons/3d-basic-rendering/introduction-to-ray-tracing/how-does-it-work introduction to ray tracing] and [https://www.scratchapixel.com/lessons/3d-basic-rendering/introduction-to-ray-tracing/implementing-the-raytracing-algorithm implementing ray tracing].		* Scratapixel's [https://www.scratchapixel.com/lessons/3d-basic-rendering/introduction-to-ray-tracing/how-does-it-work introduction to ray tracing] and [https://www.scratchapixel.com/lessons/3d-basic-rendering/introduction-to-ray-tracing/implementing-the-raytracing-algorithm implementing ray tracing].
	* [http://www.pbr-book.org/3ed-2018/Introduction/Photorealistic_Rendering_and_the_Ray-Tracing_Algorithm.html Photorealistic rendering and the ray tracing algorithm] from [http://www.pbr-book.org/3ed-2018/contents.html Physically Based Rendering: From Theory To Implementation] by Matt Pharr, Wenzel Jakob, and Greg Humphreys.		* [http://www.pbr-book.org/3ed-2018/Introduction/Photorealistic_Rendering_and_the_Ray-Tracing_Algorithm.html Photorealistic rendering and the ray tracing algorithm] from [http://www.pbr-book.org/3ed-2018/contents.html Physically Based Rendering: From Theory To Implementation] by Matt Pharr, Wenzel Jakob, and Greg Humphreys.
	* [https://cs.stanford.edu/people/eroberts/courses/soco/projects/1997-98/ray-tracin
	~~g/implementation.html Exercise on ray tracing] from~~

			Godot's SPFGI
	~~http://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf~~		* [https://godotengine.org/article/godot-40-gets-sdf-based-real-time-global-illumination Godot gets SDF-based real time global illumination]
			* http://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf
			* http://jamie-wong.com/2016/07/15/ray-marching-signed-distance-functions/
			* https://deepai.org/publication/signed-distance-fields-dynamic-diffuse-global-illumination
	Godot ~~doesn~~'~~t do ray tracing. But it is gaining support for some more~~
	~~advanced lighting techniques:~~

	https://godotengine.org/article/godot-40-gets-sdf-based-real-time-global-illumination
	http://jamie-wong.com/2016/07/15/ray-marching-signed-distance-functions/

	~~More on SDF~~

	https://deepai.org/publication/signed-distance-fields-dynamic-diffuse-global-illumination


	~~Other graphics resources~~


	~~Ray tracing exercise~~
	~~https://cs.stanford.edu/people/eroberts/courses/soco/projects/1997-98/ray-tracin~~
	~~g/implementation.html~~

	==Notes==		==Notes==

Soma: /* Resources */

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Resources

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	==Resources==		==Resources==

	* Sarah Abraham's [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures.html Computer Graphics lecture notes], especially her notes on [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures/cs354-4.pdf ray tracing] and [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures/cs354-raytracing_pseudocode.pdf ray tracing pseudocode].		* Sarah Abraham's [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures.html Computer Graphics lecture notes], especially her notes on [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures/cs354-4.pdf basic ray tracing] and [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures/cs354-raytracing_pseudocode.pdf ray tracing pseudocode].
	* Scratapixel's [https://www.scratchapixel.com/lessons/3d-basic-rendering/introduction-to-ray-tracing/how-does-it-work introduction to ray tracing].		* Scratapixel's [https://www.scratchapixel.com/lessons/3d-basic-rendering/introduction-to-ray-tracing/how-does-it-work introduction to ray tracing] and [https://www.scratchapixel.com/lessons/3d-basic-rendering/introduction-to-ray-tracing/implementing-the-raytracing-algorithm implementing ray tracing].
			* [http://www.pbr-book.org/3ed-2018/Introduction/Photorealistic_Rendering_and_the_Ray-Tracing_Algorithm.html Photorealistic rendering and the ray tracing algorithm] from [http://www.pbr-book.org/3ed-2018/contents.html Physically Based Rendering: From Theory To Implementation] by Matt Pharr, Wenzel Jakob, and Greg Humphreys.
			* [https://cs.stanford.edu/people/eroberts/courses/soco/projects/1997-98/ray-tracin
			g/implementation.html Exercise on ray tracing] from


	http://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf		http://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf
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	Other graphics resources		Other graphics resources
	~~https://www.scratchapixel.com/lessons/3d-basic-rendering/introduction-to-ray-tracing/implementing-the-raytracing-algorithm~~

	~~http://www.pbr-book.org/3ed-2018/Introduction/Photorealistic_Rendering_and_the_Ray-Tracing_Algorithm.html~~

	Ray tracing exercise		Ray tracing exercise

Soma: Created page with "==Resources== * Sarah Abraham's [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures.html Computer Graphics lecture notes], especially her notes on [https://www.cs.ut..."

2021-03-23T21:30:25Z

Created page with "==Resources== * Sarah Abraham's [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures.html Computer Graphics lecture notes], especially her notes on [https://www.cs.ut..."

New page

==Resources==

* Sarah Abraham's [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures.html Computer Graphics lecture notes], especially her notes on [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures/cs354-4.pdf ray tracing] and [https://www.cs.utexas.edu/~theshark/courses/cs354/lectures/cs354-raytracing_pseudocode.pdf ray tracing pseudocode].
* Scratapixel's [https://www.scratchapixel.com/lessons/3d-basic-rendering/introduction-to-ray-tracing/how-does-it-work introduction to ray tracing].

http://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf

Godot doesn't do ray tracing. But it is gaining support for some more
advanced lighting techniques:

https://godotengine.org/article/godot-40-gets-sdf-based-real-time-global-illumination
http://jamie-wong.com/2016/07/15/ray-marching-signed-distance-functions/

More on SDF

https://deepai.org/publication/signed-distance-fields-dynamic-diffuse-global-illumination

Other graphics resources
https://www.scratchapixel.com/lessons/3d-basic-rendering/introduction-to-ray-tracing/implementing-the-raytracing-algorithm

http://www.pbr-book.org/3ed-2018/Introduction/Photorealistic_Rendering_and_the_Ray-Tracing_Algorithm.html

Ray tracing exercise
https://cs.stanford.edu/people/eroberts/courses/soco/projects/1997-98/ray-tracin
g/implementation.html

==Notes==

<pre>
Ray Tracing
-----------

Key questions:
- how does it work?
- why is it so slow?

How does light work, really?

"Ground truth" for how light works is Quantum Electrodynamics
- i.e., quantum mechanics for electromagnetism

QED
- you have photons, and you have electrons
- photons are absorbed by electrons, and then they are emitted by electrons
- when absorbed, electrons go to "higher" orbitals (higher energy)
- when an electron moves to a lower energy orbital, it emits a photon

so, to model light, ultimately we're modeling how electrons and photons interact

Where does color come in?
- frequency, i.e. energy, of photons
- have to be in a specific frequency band to be visible light photons

So, for rendering, why does this matter?
- how things look is determined by how photons bounce around
- their energy, hence their color, changes as they bounce around
- brightness is how many photons you get

Light is painful to model entirely because
- there are LOTS of photons
- they bounce EVERYWHERE
- and this all affects how things look

Perceived color is contextual
- you don't know the color of anything until you know what its surroundings look like
- human color perception is all about correcting for this

physicists will say that photons have specific colors, i.e., their frequency
- but actually, we perceive light based on the color of objects

Something that is "red" will not emit red light (unless it is a light source). Instead, our
brains model the scene and figure out it is red based on context
- because different energy (color) photons will be emitted depending on
lighting conditions

Dim light, different color light (indoor vs sunlight), all affect the "energy" of photons but
we can tell the difference, we see the same color.

So even a pure physics-based model isn't enough, have to take into account human perception

This is all to say that ray tracing has its benefits, but is far from a completely general solution
- we'll discuss this more

Ray tracing, we start with a received "photon", and we trace back its path to a light source
- optimization, as we don't care about light that can't be perceived

rays won't follow a direct path
- interesting lighting effects come from how the rays bounce around
- have to account for much (but not all) of this bouncing

Part of the complexity is the recursive nature of the ray tracing algorithm

The other part is how rays interact with surfaces
- they are diffracted and reflected

Earlier CGI tends to focus on reflections
- think Terminator 2
- a fully reflective surface is "easiest", i.e., liquid metal
- because we just have to model the surface as rays bouncing off at
angles defined by the surface

The real world is filled with surfaces that "capture" photons
- they bounce around inside the object before releasing the photons

Movies use ray tracing with complex material models

But then, how are we doing "real time" ray tracing?
- we're fast enough to do a lot of this recursion and support
non-trivial surface models

Regular lighting algorithms are not recursive at all
- We at most consider one bounce
- we often model surfaces as "self lighting"

Godot does not support ray tracing currently
- but this isn't that much of a disadvantage now, since it is rarely used
in practice, and only in limited ways