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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I love Ralph Lauren. As I travel so much, I prefer to shop online.

Rachel Cusk's books are like pop-up volumes for grown-ups, the prose springing out of the page to bop you neatly between the eyes with its insights.

I have a similar issue with people who hire me as I do with women. 'You have to have a particular taste to want to be around me. I have a slightly askew view.

Bookstores should be located not only on campuses or on main drags, but at the assembly plant's gates, also.

I like the gizmos that transport people.

Income should be taxed one time at one rate, not again and again.

It's no treat being in bed with me.

Suppose we were able to share meanings freely without a compulsive urge to impose our view or conform to those of others and without distortion and self-deception. Would this not constitute a real revolution in culture.

I don't want to see Superman replaced with Superboy.

Success isn't just about what you accomplish in your life; it's about what you inspire others to do.

Some souls just understand each other upon meeting.

I wrote 'Zeuglodon' on a whim. I found myself writing the voice of an 11-year-old girl. I don't know why.

He likes your soft touch. He likes to feel your skin on his skin. Lay on him when his shirt is off. Embrace him and make sure your hands reach some skin. Whether your hands are cold or hot hell enjoy it.

But I believe we have a higher level of mentality within us, but we have to use the power in the right way.

I cannot understand how the education of this United States of America has been fooled time and time again. Either make it separate but equal or integrate, therefore it will be equal. And it has been separate and unequal.

For any new leader of any party at any given time it takes time if you are not in government to establish yourself.

Touring is really a pretty lonely business.

Your man wants to know that theres nothing you wouldnt do for him if thats your committed relationship.

Anyone who thinks that they are too small to make a difference has never tried to fall asleep with a mosquito in the room.

I would love to write a mystery - a romantic, funny mystery.

If you ask any great player or great quarterback, there's a certain inner confidence that you're as good as anybody. But you can't say who is the absolute best. To be considered is special in itself.

Israel's foreign policy has three points: the relationship with the U.S., the relationship with the U.S., and the relationship with the U.S.

After a while, your cheap talk don't even cause me pain, so let your bullets fly like rain.

In the film, I'm not very mobile, like in the space suit.