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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That's been the most exciting part of the show - incorporating the magic and the acrobats and the singing and dancing to make our 'Pippin.'

The most likely victim of actual religious discrimination in British society is a Muslim, but the person who is most likely to feel slighted because of their religion is an evangelical Christian.

I don't even know how many times I auditioned for Danny Zuko in 'Grease.'

The product cycle for the Oculus Rift will be between the rapid six-month cycle of cell-phones and the slower seven-year cycle of consoles. It's rare to see a phone not coming out every year.

Faith is what makes life bearable, with all its tragedies and ambiguities and sudden, startling joys.

Revolution is like Saturn, it devours its own children.

When we were shooting 'The Book Thief,' I was keeping all these journals. And I remember talking to my mom, really trying to verbalize all the experiences I was having. And I remember my mom saying, 'Ben, reflection is a retroactive process.' When you're going through it, that's the time to just let it wash over you.

We must forgive each other our arising for our existence always torments others. The golden rule in the midst of this mutual misery has always been not to do no harm but as little as possible and not to love one another but as much as you can.

I do not think that the educational program of our schools should be determined by what the community thinks it needs.

I'm a hopeless romantic, and very much the person in a relationship to go: If things are going well, I'll buy the flowers, remember the dates of things, plan fun nights out.

When you're doing sketch comedy and you're pregnant, it's like wearing a giant sombrero in every sketch.

Self awareness and self esteem. Those aren't female issues, those are human issues.

Injustice, poverty, slavery, ignorance - these may be cured by reform or revolution. But men do not live only by fighting evils. They live by positive goals, individual and collective, a vast variety of them, seldom predictable, at times incompatible.

In pure literature, the writers of the eighteenth century achieved, indeed, many triumphs; but their great, their peculiar, triumphs were in the domain of thought.

I didn't wake up and decide to become an activist. But you couldn't help notice the inequities, the injustices. It was all around you.

All girls know that they can be anything now. That transformation is to me one of the most satisfying things.

Achieving gender equality requires the engagement of women and men, girls and boys. It is everyone's responsibility.

Well, I'm a Harley Babe.

Now, you tell me, if I have a day off during the baseball season, where do you think I'll spend it? The ballpark. I still love it. Always have, always will.

I'm not here to try and replace anyone or compete with anyone.

I'm not one to think of burying my head in the sand - I've always been a positive person and still am now.

I felt unworthy to play Jesus. I just accepted the responsibility and said, 'What actor wouldn't want to play this role?'

Truth is life's most precious commodity.

Teachers are not supposed to be repositories of information which they dish out. That is from an age when there were no other repositories of information, other than books or teachers, neither of which were portable. A lot of my big task is retraining these teachers.