ins and outs 2 Each shader can specify inputs and outputs using those keywords and wherever an output variable matches with an input variable of the next shader stage they're passed along. The vertex and fragment shader differ a bit though

Shaders are also very isolated programs in that they're not allowed to communicate with each other; the only communication they have is via their inputs and outputs.

Shaders always begin with a version declaration, followed by a list of input and output variables, uniforms and its main function. Each shader's entry point is at its main function where we process any input variables and output the results in its output variables

GLSL types

GLSL Vector Container A vector in GLSL is a 1,2,3 or 4 component container for any of the basic types just mentioned. They can take the following form (n represents the number of components)

Components of a vector can be accessed via vec.xwhere x is the first component of the vector. You can use .x, .y, .z and .w to access their first, second, third and fourth component respectively. GLSL also allows you to use rgba for colors or stpq for texture coordinates, accessing the same components.

The vector datatype allows for some interesting and flexible component selection called swizzling. Swizzling allows for the following syntax:

We can also pass vectors as arguments to different vector constructor calls, reducing the number of arguments required:

ins and outs Shaders are nice little programs on their own, but they are part of a whole and for that reason we want to have inputs and outputs on the individual shaders so that we can move stuff around. GLSL defined the in and out keywords specifically for that purpose.

If we want to send data from one shader to the other we'd have to declare an output in the sending shader and a similar input in the receiving shader. When the types and the names are equal on both sides OpenGL will link those variables together and then it is possible to send data between shaders

Uniforms Uniforms are another way to pass data from our application on the CPU to the shaders on the GPU

To declare a uniform in GLSL we simply add the uniform keyword to a shader with a type and a name. From that point on we can use the newly declared uniform in the shader. Let's see if this time we can set the color of the triangle via a uniform

If you declare a uniform that isn't used anywhere in your GLSL code the compiler will silently remove the variable from the compiled version which is the cause for several frustrating errors; keep this in mind!

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Being thought of as sexy makes one employable, but it's not going to last forever, so I try not to think about it. It's like something that exists outside of me.

I definitely don't want to be one of those athletes who turns into a cheesy actress.

The fight is always the same within the Democratic Party, isn't it? The more things change, the more they stay the same.

Vivid images are like a beautiful melody that speaks to you on an emotional level. It bypasses your logic centers and even your intellect and goes to a different part of the brain.

I found college useful for a lot of other reasons. It exposed me to a great many influences I wouldn't otherwise have encountered, and gave me a lot of time with some very intelligent people whose thoughts are still with me.

On a TV show, you don't know where the character is going.

Willie Nelson is not just a star or a headliner, he's a legend.

The more I have written, the less it has been about exploring myself, and the more it has been about exploring the world around me.

The Wii U is pretty cool, and the thing that I'm most intrigued about it is it's the first gaming platform that actually is exploiting the second screen.

My 'go to' workout is called the Asylum from Beach Body. It's intense training with lots of intervals, core work. It's hard! I travel a lot, so I can take it on the road with me and do it in a hotel room.

"Thoughtless" minds are "pocket-less" beings.

My style is bad white-boy dancing. I can do swing a little bit, but nothing beyond that. My solo dancing is sad. I use my arms, badly.

Boxing is changing and training methods are slowly being dragged into the 21st century.

I grew up in a farming family. I hated cleaning out the chickens but loved hatching them and feeding the new born sheep. The smell of hot milk still has a special resonance for me. Harvest was back-breaking work, though... Where do you think Jesus got his biceps from?

Try to see the good in others. When you're tempted to judge someone, make an effort to see their goodness. Your willingness to look for the best in people will subconsciously bring it forth.

We are visual creatures. Visual things stay put, whereas sounds fade.

I know that there are going to be people that don't like my music, but I think in the industry itself it is always that, 'Oh. you're from the 'X Factor.' There have been certain radio stations that will not play your song because you are from the 'X Factor,' yet they'll play another song from an artist from another TV show.

You can't be too careful what you tell a child because you never know what he'll take hold of and spend the rest of his life remembering you by.

Sooner or later the world will have to return to the good old days when we fought wars and killed people the old fashioned way one at a time.

The end of an delusion is invariably sadness or tears

I used to tell my graduate students at Stanford, 'Don't worry about what job you have to pick because your job picks you. Let your job pick you. Find something you are passionate about. Then when you are passionate, be persistent. Just keep doing it for a while because progress is always hard work. It never rests in ideas.'

A concrete agenda and landslide victory might not even guarantee a president his mandate in a capital as polarized as Washington.

I pretty much knew that I was going to come in fourth, but then I said, 'I'm fourth at the Olympic Games. What are you talking about? Why is that disappointing?'

I like to complain and do nothing to make things better.