Jodo's i2350 blog page

[jordanuoitgamedev]

Well, the semester is coming to a close, and I thought I’d wrap up my blogs with an overview of our Game Development Workshop game - Vase. Of course, I have to relate this to our shaders course, so of course, I will be talking about the graphics techniques we used.

Vase is an isometric action...

[jordanuoitgamedev]

Ambient occlusion is a technique used in almost every 3D game today. It is used to simulate the way light radiates off of objects. In other words, it changes the brightness of certain parts of the object to simulate its environment to add realism. Here is a prism I created with a baked AO...

[jodoi2350]

Cel Shading- i2350

Cel shading is a shader technique that gives a cartoony or hand-drawn effect to a scene. It does this by averaging the colour on certain sections of the model. This is often combined with lighting calculations to achieve dynamic shading on a model.

Here is an example of cel shading on a model. The picture below is a normal mapped head with per fragment lighting.

You can definitely see certain contrasts in the brightness changes on the model. However, the lighting seems very smooth across the model.

Here is the same head, with a cel shader applied to it.

As you can see, the lighting on the head has been broken down in to 5 sections of intensity. To achieve this effect, you first need to calculate your lighting. Take a look at my object space normal mapping blog if you want to see how to calculate per fragment lighting. Once you have calculated your specular, diffuse, and ambient lighting, add the 3 together and save that value as your intensity variable. float intensity = ambient + diffuse + specular; Now we need to set a limit on the intensity, in order to get those heavy brightness changes.

if(intensity > 1.0) intensity = 1.0; else if(intensity > 0.75) intensity = 0.75; else if(intensity > 0.5) intensity = 0.5; else if(intensity > 0.25) intensity = 0.25; else intensity = 0.1; As you can see, we are cutting out the middle brightness values between each intensity. The only intensity values are going to be 1, 0.75, 0.50, 0.25, and 0.10. Now, factor your intensity value in to your final colour output. vec3 final = texture_colour * intensity; gl_FragColor.rgb = final;

And you're done! Thanks for reading. For a list of some video games that use Cel Shading, check out: http://en.wikipedia.org/wiki/List_of_cel-shaded_video_games

[jordanuoitgamedev]

Normal mapping, or bump mapping is a technique widely used in 3D games and applications. Its main purpose is to add details to a model without increasing the polygon count. The normal map of a model is a texture that essentially tells the program how light should reflect off of the model. Below...

[jordanuoitgamedev]

Though our game is already SUPER pretty (just kidding it’s was pretty ugly..) we are going to make it even more beautiful this semester by implementing shaders! Our task was to take a screenshot of our game, throw that in to Photoshop, and try to make it pretty.

Here is a photo of what the...

[jordanuoitgamedev]

For this week’s blog I will be reviewing a really awesome website that I stumbled upon while I was researching shaders! The website is a GLSL Sandbox, where users can edit and post different Web GL shaders for others to play with and learn from. Perhaps the greatest part of the website is...

[jordanuoitgamedev]

Blur and bloom are two post processing effects that are used widely in the modern games industry. Blur is used widely to simulate distorted perception due to factors such as speed, daze, fear, etc. Bloom is a technique used to replicate light artifacts commonly produced by cameras. Bloom...

[jordanuoitgamedev]

This weeks blog is on shadows, and using sprites in the place of models. I will be looking at these two features in Guild Wars 2. Shadows are a very important feature if a developer wishes to add a realistic element to their game. Though Guild Wars 2 is a fantasy game, the style is very...

[jordanuoitgamedev]

Reflection is a complex visual to mimic properly in games. To reflect an image across a plane, you need to essentially mirror that image over that plane. This means to take the vertices of the image, and flip them across the plane in to their negative or positive corresponding points (5 to -5, -19...

[jordanuoitgamedev]

Many of today’s games have some sort of particle system implemented in them. Most of the time, the particles are used to add aesthetics to the game. In this blog, I will be talking about the basic physics behind a particle system, and how to set up a particle class.

First, you will need to...

[jordanuoitgamedev]

In part 1, I covered how to set up a basic particle system. This blog will cover a couple effects that you can achieve with particles. Effect 1 - Burst

So you want to make a fancy explosion? Well you’d best start with a burst function. The burst function is a fairly simple one to write, as it...