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

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.

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.

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

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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Love is the ultimate outlaw. It just won't adhere to any rules. The most any of us can do is sign on as its accomplice.

I think once you enter the dating world and you realise it's nothing like those Disney movies you watched when you were a little girl, you just become more guarded.

True ornament is not a matter of prettifying externals. It is organic with the structure it adorns whether a person a building or a park.

I think kids are natural actors. You watch most kids; if they don't have a toy, they'll pick up a stick and make a toy out of it. Kids will daydream all the time.

I know that dancers, especially ballet dancers, can't do it forever.

I was born in Jersey City and raised in Bayonne, New Jersey. It's a town that's next to Jersey City, and I'm still there!

In 2009 we increased the cash in Quinn Direct as we had in 2008. We increased the cash in it in 2010. The outstanding claims were 20m in March 2010 but Quinn Direct had more business in the U.K. than in Ireland.

I do believe that we are to love our enemies and do good to those who persecute you. I believe that there is power and strength in that.

Quebec City is the most European of any city in North America; they speak French all the time. There is a part of town called Old Quebec which is really like being in France. The architecture is just gorgeous, food, shopping. I'd say Quebec City is the most beautiful city in North America I've seen.

People who tend to listen to my music have come back and said, 'Yo, this is my anthem. This is what I live by.'

It's important for the Fed, hard as it is, to attempt to detect asset bubbles while they're forming.

Voters crave authenticity.

Defining marriage is a power that should be left to the states. Moreover, no state should be forced to recognize a marriage that is not within its own laws, Constitution, and legal precedents.

The invisible are always so resolutely invisible, until you see them.

Let whatever is going to happen to me happen. I'm expecting the worst for myself and I'm resigned to it.

I see my actors as my collaborators.

All sorts of other lies are being spread today, I do not know what else they will invent. I've heard that I'm of Jewish descent, but I found, I knew of my ancestors in Zagorje from around 350 years ago, and I said, maybe it would be good to have some of that, I guess I would be richer, I might not have become a Communist.

I'm actually doing a show. from my shed. on the internet. but it won't be music or anything, it's more to do with drinking and smoking. it's an art piece.

Its not that hard to be glamorous in England.

When I was in my early 20s, my dream was to write mystery novels. I wanted to do what my favourite crime writer, Ross Macdonald, did - crank out a book a year. The only problem - and it was a considerable one - was that I stank.

History repeats itself.

I am strong and powerful.

It's quite hard to have your mom as a teacher - it's like, she's not necessarily a 'real teacher' for me. But she'd always teach me to really hear the music, and develop my ear, and to try and hear the harmonics of the piano.

A part of you has grown in me, together forever we shall be, never apart, maybe in distance, but not in heart.