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

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.

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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Heaven is a beautiful place to be full of beautiful people having a beautiful time

If your man is a sports enthusiast, you may have to resign yourself to his spouting off in a monotone on a prize fight, football game or pennant race.

A drawing is always dragged down to the level of its caption.

Words felt so clumsy when she was talking about feelings and not facts.

I was always shy and had a huge fear of being onstage.

My family are my priority but I've always had a strong work ethic and I like to be busy.

I always played a soldier, sailor, or policemen.

A committee is a group that keeps minutes and loses hours.

Although I generally avoid the cloyingly sweet wines, I have used them for poaching fruit.

In polite society one laughs at all the jokes, including the ones one has heard before.

A great production of a black comedy is better than a mediocre production of a comedy of errors.

There has certainly been criticism of the timing involved in getting help to the victims of the storm, and much of it may indeed be warranted. However, this is not the time for pointing fingers; rather, it is the time for offering a helping hand to our neighbors in need.

I have always known that at last I would take this road, but yesterday I did not know that it would be today.

Intelligence we gathered at the time indicated that this was in fact leadership and we struck the leadership.

It is unhappily true that much insincere Literature and Art, executed solely with a view to effect, does succeed by deceiving the public.

Anyway, stories bring us together to find common ground, to find our way through life together, or just to entertain us, and I am just thrilled to be a part of that process.

I know Barack Obama. And I believe that as president, he'll pursue the common good by seeking common ground rather than trying to divide us.

My problem is I'm an addictive personality. I can't have one coffee. I can't eat one piece of chocolate.

The Kabbalists say that the holy one of the universe is broken, and that we are extensions of the holy one and carry that brokenness inside of us. Our task is to fix our brokenness and hence the brokenness of the holy one.

The Republican consciousness has no integrity and it falls apart once you check it out. If you're a Christian, why would you want to fry this dude?

I had no preconceived idea what fame would be like, because I never thought I would be famous. I just wanted to do my work. Hell, I just wanted to pay my rent on time.

How rich our German life is compared to France or England: what an abundance of social types and customs with completely different origins... Germany is a world, whereas England and France, with their stereotypically divided three social classes, are but enlarged villages... what a stage for a Balzac.

Sister is our first friend and second mother

Fathers and mothers have lost the idea that the highest aspiration they might have for their children is for them to be wise... specialized competence and success are all that they can imagine.