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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At the end of the day, I believe truth is stronger than any lie that's out there.

The spirit of Southwest Airlines is exuberant, it's caring, it's dedicated, it's diligent, it's fun, it's rewarding, it's a joy.

To guarantee the individual maximum freedom within a social frame of minimal laws ensures - if not happiness - its hopeful pursuit.

We went to the British Museum, and I was looking up my family in the books - pages and pages on it.

When the ship goes down, the waves very quickly roll over the top of it, and attention shifts elsewhere. It's just the natural order of things in TV - in life - and is as it should be.

I've been incredibly fortunate to be able to have different opportunities and be able to choose, which is kind of amazing.

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The NSA has the greatest surveillance capabilities in American history... The real problem is that they're using these capabilities to make us vulnerable.

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Judges pretty much act independently once they get on the bench so I'm not really sure why Harper's concerned that the court is currently being stacked with a lot of Liberal appointments.

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Speaker Pelosi says unemployment benefits are economic stimulus. Those are bare-bones benefits.

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I was a team sports guy, but I don't do that anymore. When I work out, it's alone.

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The international community can't trust such a government. If the government of Iran wants the international community to believe in what it says, it should try to bring true, pure democracy into the country. The political solution to the energy issue or the nuclear case is democracy in Iran.