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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I'm not naturally manipulative.

That even an apocalypse can be made to seem part of the ordinary horizon of expectation constitutes an unparalleled violence that is being done to our sense of reality, to our humanity.

I think it's good not to make demands on the reader too early. But as the poem goes on, I want the journey of the poem to lead into some interesting places.

Retired is being tired twice Ive thought first tired of working then tired of not.

Funerals are pretty compared to death. Funerals are quiet but deaths not always.

If a patron buys from an artist who needs money, the patron then makes himself equal to the artist; he is building art into the world; he creates.

If you have a bad day in baseball, and start thinking about it, you will have 10 more.

They say eyes clear with age.

Affirmations need to be used if they are to become incorporated into the fabric of your being.

Auditioning is the worst.

To a degree the Greek and Roman mythological heroes are just the first superheroes. They appeal to children for much the same reason. These gods and heroes may have powers but they get angry and they do the wrong thing. They are human too.

Mother love is the fuel that enables a normal human being to do the impossible.

The choice between a Labour government and a Tory one is sharpening minds.

Working hard and working smart sometimes can be two different things.

Our femtosecond snapshots can examine a molecule at discrete instants in time.

As a former minority leader who became the first Republican Speaker of the House in Florida since Reconstruction, I know that leadership is not an easy task.

My family had a membership to the Riverside Yacht Club where my brother, Sandy, learned to sail, and I competed in local swim races. My sister, Marcia, became a competitive springboard diver, and my brother excelled in water polo.

I've been obsessed with demons since reading 'The Elfstones of Shannara' and 'Master of the Five Magics' by Lyndon Hardy.

30058 is the ZIP Code I grew up in in Atlanta, so the music represents where I'm from, and the mindset of '30058.' It's got a touch of reggae and a hip-hop feel. It's soothing, I think.

I get out of the pool after a workout and look on my BlackBerry to see if the nanny called and to make sure everything's okay. My child is always on my mind.

My daughter's favorite musical is 'Wicked,' which she has seen hundreds of times - she even worked as an usher at the Pantages so she could see it over and over. Her dream is to play Elphaba.

You don't like to be lied to, by your friends or in your business dealings. So why would you want to be lied to when it comes to the origin of life or the fate of the planet?

For a startup, you need to stay small so the others don't attack, or you aim to be one of the big guys. If you don't do it right, you might lose everything.

For me, Lancome was more than just a brand. There was something very nostalgic about the name, about the whole story.