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dkotfis Nov 10, 2014
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dkotfis Nov 12, 2014
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249 changes: 47 additions & 202 deletions README.md
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------------------------------------------------------------------------------
CIS565: Project 6 -- Deferred Shader
-------------------------------------------------------------------------------
CIS 565 Project6 : Deferred Shader
===================

Fall 2014
-------------------------------------------------------------------------------
Due Wed, 11/12/2014 at Noon
-------------------------------------------------------------------------------

-------------------------------------------------------------------------------
NOTE:
-------------------------------------------------------------------------------
This project requires any graphics card with support for a modern OpenGL
pipeline. Any AMD, NVIDIA, or Intel card from the past few years should work
fine, and every machine in the SIG Lab and Moore 100 is capable of running
this project.

This project also requires a WebGL capable browser. The project is known to
have issues with Chrome on windows, but Firefox seems to run it fine.

-------------------------------------------------------------------------------
INTRODUCTION:
-------------------------------------------------------------------------------

In this project, you will get introduced to the basics of deferred shading. You will write GLSL and OpenGL code to perform various tasks in a deferred lighting pipeline such as creating and writing to a G-Buffer.

-------------------------------------------------------------------------------
CONTENTS:
-------------------------------------------------------------------------------
The Project5 root directory contains the following subdirectories:

* js/ contains the javascript files, including external libraries, necessary.
* assets/ contains the textures that will be used in the second half of the
assignment.
* resources/ contains the screenshots found in this readme file.

This Readme file edited as described above in the README section.

-------------------------------------------------------------------------------
OVERVIEW:
-------------------------------------------------------------------------------
The deferred shader you will write will have the following stages:

Stage 1 renders the scene geometry to the G-Buffer
* pass.vert
* pass.frag

Stage 2 renders the lighting passes and accumulates to the P-Buffer
* quad.vert
* diffuse.frag
* diagnostic.frag

Stage 3 renders the post processing
* post.vert
* post.frag

Author: Dave Kotfis

[Click Here For A Demo](http://dkotfis.github.io/Project6-DeferredShader/index.html)

Visit [Youtube](http://youtu.be/4bRB2lEsQBo) to checkout a video of it running.

##Overview

This project features special rendering effects that can be performed efficiently through a deferred shading pipeline using WebGL. Effects include Toon Shading, Bloom Shading, and Screen Space Ambient Occlusion.

The pipeline involves an initial pass to create the geometry buffer (g-buffer) consisting of positions, normals, material color, and depth. Then, a shading pass is performed that uses blinn-phong shading (or diffuse only). Finally, a third pass is used for additional special effects. An alternate diagnostic pass can be used to render the g-buffer for debug purposes.

The result with diffuse shading only with no added effects looks like this:

![Diffuse Only] (renders/diffuse.png)

##Toon Shading

Toon Shading makes the render look cartoonish, where only a few discrete shades of color are used, and the edges of objects have thick, pencil-drawn borders. I implemented this in the post processing shader by first quantizing the color shade into a discrete number of colors. I then detected edges by using a high pass filter (subtracting out blur) on the depth buffer. I draw anything with a edge score above a certain threshold as black.

![Toon Shading] (renders/nice-toon.png)

##Bloom Shading

Bloom shading can make materials appear to glow. It does this by taking a luminosity texture to create a glow buffer, then blur the glow. For a single object, I treated the entire thing as glowing, which allowed me to use the original material color in the g-buffer as the glow buffer. I then used a gaussian convolution on this glow and added it to the original color.

![Bloom Shading] (renders/bloom.png)

##Screen Space Ambient Occlusion

Inspired by the Crytek approach, I implemented SSAO by generating 100 direction samples in the hemisphere of the normal of each point. These are scaled to prioritize shorter radius samples. These samples are used to check nearby points to see if casting a ray would collide with the surface and fail the depth test. The occlusion factor is the percentage of the rays that are occluded. Here are comparison images of a scene without and with SSAO. Notice the shaded areas such as the ears and mouth.

![Without SSAO] (renders/no-ao.png)
![SSAO] (renders/with-ao.png)

##G-Buffer Optimization

I have attempted to optimize the G-Buffer by condensing the normal down into only y and z components, inferring the x coordinates through normalization in the shading and post processing passes. However, I found that without an increase in resolution to the y and z components, there is not enough precision to accurately compute the third component. When using the data in this form in the blinn-phong shading only, a strange glow would happen depending on the screen space position of the model, where the precision was particularly bad for the pow and sqrt functions on the GPU. There seemed to be little to be gained on this route.


The keyboard controls are as follows:
WASDRF - Movement (along w the arrow keys)
Expand All @@ -69,156 +59,11 @@ WASDRF - Movement (along w the arrow keys)
* 2 - Normals
* 3 - Color
* 4 - Depth
* 5 - No Effects (Blinn-Phong Only)
* 6 - Toon Shading
* 7 - Screen Space Ambient Occlusion
* 8 - Bloom Shading
* 0 - Full deferred pipeline

There are also mouse controls for camera rotation.

-------------------------------------------------------------------------------
REQUIREMENTS:
-------------------------------------------------------------------------------

In this project, you are given code for:
* Loading .obj file
* Deferred shading pipeline
* GBuffer pass

You are required to implement:
* Either of the following effects
* Bloom
* "Toon" Shading (with basic silhouetting)
* Screen Space Ambient Occlusion
* Diffuse and Blinn-Phong shading

**NOTE**: Implementing separable convolution will require another link in your pipeline and will count as an extra feature if you do performance analysis with a standard one-pass 2D convolution. The overhead of rendering and reading from a texture _may_ offset the extra computations for smaller 2D kernels.

You must implement two of the following extras:
* The effect you did not choose above
* Compare performance to a normal forward renderer with
* No optimizations
* Coarse sort geometry front-to-back for early-z
* Z-prepass for early-z
* Optimize g-buffer format, e.g., pack things together, quantize, reconstruct z from normal x and y (because it is normalized), etc.
* Must be accompanied with a performance analysis to count
* Additional lighting and pre/post processing effects! (email first please, if they are good you may add multiple).

-------------------------------------------------------------------------------
RUNNING THE CODE:
-------------------------------------------------------------------------------

Since the code attempts to access files that are local to your computer, you
will either need to:

* Run your browser under modified security settings, or
* Create a simple local server that serves the files


FIREFOX: change ``strict_origin_policy`` to false in about:config

CHROME: run with the following argument : `--allow-file-access-from-files`

(You can do this on OSX by running Chrome from /Applications/Google
Chrome/Contents/MacOS with `open -a "Google Chrome" --args
--allow-file-access-from-files`)

* To check if you have set the flag properly, you can open chrome://version and
check under the flags

RUNNING A SIMPLE SERVER:

If you have Python installed, you can simply run a simple HTTP server off your
machine from the root directory of this repository with the following command:

`python -m SimpleHTTPServer`

-------------------------------------------------------------------------------
RESOURCES:
-------------------------------------------------------------------------------

The following are articles and resources that have been chosen to help give you
a sense of each of the effects:

* Bloom : [GPU Gems](http://http.developer.nvidia.com/GPUGems/gpugems_ch21.html)
* Screen Space Ambient Occlusion : [Floored
Article](http://floored.com/blog/2013/ssao-screen-space-ambient-occlusion.html)

-------------------------------------------------------------------------------
README
-------------------------------------------------------------------------------
All students must replace or augment the contents of this Readme.md in a clear
manner with the following:

* A brief description of the project and the specific features you implemented.
* At least one screenshot of your project running.
* A 30 second or longer video of your project running. To create the video you
can use [Open Broadcaster Software](http://obsproject.com)
* A performance evaluation (described in detail below).

-------------------------------------------------------------------------------
PERFORMANCE EVALUATION
-------------------------------------------------------------------------------
The performance evaluation is where you will investigate how to make your
program more efficient using the skills you've learned in class. You must have
performed at least one experiment on your code to investigate the positive or
negative effects on performance.

We encourage you to get creative with your tweaks. Consider places in your code
that could be considered bottlenecks and try to improve them.

Each student should provide no more than a one page summary of their
optimizations along with tables and or graphs to visually explain any
performance differences.

-------------------------------------------------------------------------------
THIRD PARTY CODE POLICY
-------------------------------------------------------------------------------
* Use of any third-party code must be approved by asking on the Google groups.
If it is approved, all students are welcome to use it. Generally, we approve
use of third-party code that is not a core part of the project. For example,
for the ray tracer, we would approve using a third-party library for loading
models, but would not approve copying and pasting a CUDA function for doing
refraction.
* Third-party code must be credited in README.md.
* Using third-party code without its approval, including using another
student's code, is an academic integrity violation, and will result in you
receiving an F for the semester.

-------------------------------------------------------------------------------
SELF-GRADING
-------------------------------------------------------------------------------
* On the submission date, email your grade, on a scale of 0 to 100, to Harmony,
[email protected], with a one paragraph explanation. Be concise and
realistic. Recall that we reserve 30 points as a sanity check to adjust your
grade. Your actual grade will be (0.7 * your grade) + (0.3 * our grade). We
hope to only use this in extreme cases when your grade does not realistically
reflect your work - it is either too high or too low. In most cases, we plan
to give you the exact grade you suggest.
* Projects are not weighted evenly, e.g., Project 0 doesn't count as much as
the path tracer. We will determine the weighting at the end of the semester
based on the size of each project.


---
SUBMISSION
---
As with the previous projects, you should fork this project and work inside of
your fork. Upon completion, commit your finished project back to your fork, and
make a pull request to the master repository. You should include a README.md
file in the root directory detailing the following

* A brief description of the project and specific features you implemented
* At least one screenshot of your project running.
* A link to a video of your project running.
* Instructions for building and running your project if they differ from the
base code.
* A performance writeup as detailed above.
* A list of all third-party code used.
* This Readme file edited as described above in the README section.

---
ACKNOWLEDGEMENTS
---

Many thanks to Cheng-Tso Lin, whose framework for CIS700 we used for this
assignment.

This project makes use of [three.js](http://www.threejs.org).
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