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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Few places on earth have been as affectionately alchemised into literature as the Lake District.

I wouldn't exactly call it 'cooking' but I can make noodles. That means I can boil water, put the pasta in and wait until it's done.

I think it's hilarious if people say that my body looks masculine.

Take the trouble to stop and think of the other person's feelings, his viewpoints, his desires and needs. Think more of what the other fellow wants, and how he must feel.

Vision is the art of seeing what is invisible to others.

I would love to be in a Jimmy McGovern drama on TV, but there is no way he would ever ask me unless it would be to play a lawyer or something.

Our fans make the band. What they give we give right back. They're an integral part of us. They ARE us.

We need to focus on building up our own nation and creating jobs here at home.

Youre a winner. The tests of life are not meant to break you but to make you.

I never took any vocal training.

Laughter is a powerful weapon for it carries the light. To laugh is to defy the darkness.

I've been in eleven no-hitters you know.

I don't think I have advice for female directors as opposed to male directors. I think all first-time directors should try and be as prepared as they possibly can, because it's hard!

Brains are better than brawn.

The thing that's funny is that everyone thinks I'm dead.

I don't sit down to write a funny story. Every single thing I sit down to write is meant to be sad.

As a public official and being so highly visible, I have a responsibility to make it very clear that those people who will have cancer at one point in their lives will be able to function.

Life's a game made for everyone, and love is the prize.

Everything is changing. People are taking their comedians seriously and the politicians as a joke.

If you love it, and work really hard at it, it will really happen, I believe. I'm living proof.

We have to choose faith even if we don't feel it. Or hold on to a friend who has faith.

I have an A rating from the NRA.

Disability is a matter of perception. If you can do just one thing well youre needed by someone.

I love Dead Ringers. A democratic set, the work was taken seriously.