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.

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 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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I have learned that I will not pay any attention to anything people say about my movies, because people say things that are all over the place.

On the one hand, the idea of marriage and the sort of traditional family life repulses me. But on the other hand, I long for it, you know what I mean? I'm constantly in conflict with things. And it is because of my past and my upbringing and the journey that I've been on.

I love filming in London. In New York, every street is familiar because you have seen it in a movie. They mythologise their own city. You're forever trying to get down streets that have been blocked off because of shooting. In London, they don't put up with it; they're grumpy.

By the time I am Howard's age I hope to be long retired. I don't plan on working that long.

From the night, his solitude, the poet finds day and starts a diary that is lethal to the inert. The dark landscape yields a dialogue.

Only he who has seen better days and lives to see better days again knows their full value.

I used to write at home, but it didn't ever occur to me to be a writer.

Comics shouldn't be 'tools' for anyone's agenda except for the characters. And I am speaking only of super hero action comics. I love many of the alternative comics that are like journalistic stories. Documentary comics, a mix of reportage and fiction. Those are just great.

Every writer hopes or boldly assumes that his life is in some sense exemplary, that the particular will turn out to be universal.

Ive gone fishing thousands of times in my life and I have never once felt unlucky or poorly paid for those hours on the water.

Tobacco is the passion of honest men and he who lives without tobacco is not worthy of living.

We all wanted to copy Vivien Leigh.

Happiness doesn't depend on any external conditions, it is governed by our mental attitude.

We must remember that North Carolina is more than a collection of regions and people. We are one state, one people, one family, bound by a common concern for each other.

If we look at the life cycle of technologies, we see an early period of over-enthusiasm, then a 'bust' when disillusionment sets in, followed by the real revolution.

Not a lot of individuals get to refer to the Lord in their prayers as 'Dude', but he's doing a new thing with me.

Dogma in power does have a unique chilling ingredient not exhibited by power however ghastly wielded for its own traditional sake.

Always the beautiful answer who asks a more beautiful question.

Comedy isn't necessarily all dialogue. Think of Buster Keaton: the poker face and all this chaos going on all around him. Sometimes it's a question of timing, of the proper rhythm.

There are different rules for reading, for thinking, and for talking. Writing blends all three of them.

I'm all about building a relationship with viewers and getting to know them.

God continues to lift the curtain and allow the enemies of America to give us probably what we deserve.

I'd said to my sweetheart a couple of days before that the SAG and Spirit Award nomination was amazing and I had no attachment to the Academy Award. I knew I was an underdog so I just decided to sleep through the announcement.

There is no time like the old time, when you and I were young.