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 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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When you're a kid and your father is an engineer, he goes to the office. I saw my father get up and go to the office in the house and write. But I don't see any similarities.

Green fingers are the extension of a verdant heart.

To trap one's self-suffering is to risk being devoured from the inside.

We're not saying that you don't need coal, but when you do mine the coal there are responsibilities to it. It may cost a little more, but it is the right thing to do.

Never be afraid to fall apart because it is an opportunity to rebuild yourself the way you wish had been all along.

'Champagne' and 'breathmint' are the first two words all Oscar winners hear.

Ask anyone who has been in a love relationship for a while nothing is perfect.

Chloe is really just like an exaggerated aspect of myself.

Most people might just as well buy a share of the whole market, which pools all the information, than delude themselves into thinking they know something the market doesn't.

You kind of forget he's Peter Jackson in a way because he's so normal; he's lovely. It's like having a friend direct you, except it's Peter Jackson.

When ones expectations are reduced to zero one really appreciates everything one does have.

People cheer the Bible, buy the Bible, give the Bible, own the Bible - they just don't actually read the Bible.

I think we must all feel that there are people out there who know things about our young selves, you know, our early, early lives, that no one else can ever know.

I don't think the tabloids find me very interesting.

Ceremonies are different in every country, but true politeness is everywhere the same.

Don't waste your life in doubts and fears: spend yourself on the work before you, well assured that the right performance of this hour's duties will be the best preparation for the hours or ages that follow it.

What we do is just race hard on the track every week. That's the way I'd like it to be documented, and if we watch the tape, we'll see that the No. 48 swerved into us first and I know that, before even watching the tape.

No one who is at all acquainted with the Indian in his home can deny that we are a polite people.

All relationships change the brain - but most important are the intimate bonds that foster or fail us, altering the delicate circuits that shape memories, emotions and that ultimate souvenir, the self.

Fortune truly helps those who are of good judgment.

I am proud of myself.

For everyone I know who is a writer, there was some awkward time in their lives when they had to learn to call themselves one.

Swimming is a confusing sport, because sometimes you do it for fun, and other times you do it to not die. And when I'm swimming, sometimes I'm not sure which one it is.

I was too ashamed and afraid to confide in friends, and wanted to convince others and myself that my marriage was a success. I lost myself in my writing. Finding ways for my characters to overcome their problems and make their relationships work helped plaster over the wound caused by my inability to make things right at home.