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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What's the difference between sex and love? I have four wives and five kids. I apparently don't know the difference.

Not only the priceless heritage of our fathers, of our seamen, of our Empire builders is being thrown away in a war that serves no British interests - but our alliance leader Stalin dreams of nothing but the destruction of that heritage of our fathers?

You should do what you enjoy doing, what brings you passion. As kids, we spontaneously sing and dance and tell stories, and along the way, someone comes and says, 'No. You shouldn't be doing that.' And we slowly begin to unlearn our passions. I think you have to hold on to those things.

Success without fulfillment is failure.

Trying to block women from getting access to contraception or defunding Planned Parenthood is completely nonsensical from a policy standpoint.

I truly believe the things Notre Dame stands for.

To have a childhood surrounded by people like Sir Laurence Olivier and Vivien Leigh sounds glitzy, but for years I wanted to repress it. I couldn't take that kind of power and success.

Any good apology has 3 parts: 1)I'm sorry 2)It's my fault 3)What can I do to make it right? Most people forget the third part.

Biofuels such as ethanol require enormous amounts of cropland and end up displacing either food crops or natural wilderness, neither of which is good.

In the past, I'd sort of know before Ozzy sang something, what he was going to sing. I'd know what sort of way a melody was going to go 'cause of the way he'd approach it.

In the real world in which we live, it's a dangerous world. And you know the old saying is that we have to be right 100 percent of the time; the terrorists only have to be right once.

I was brought up in a tenement house in a working district. We didn't even have a bathroom! We had a gaslight in the hallway and a black-and-white TV.

I apologize when I'm wrong.

There's nothing wrong with doing comedies, and I'm not against comedies, either, but I always want to do stuff that keeps me off my guard and gets me out of my comfort zone.

Nations without a past are contradictions in terms. What makes a nation is the past, what justifies one nation against others is the past, and historians are the people who produce it.

I have had time to analyze my feelings. I am certain that they are totally neurotic, sexist, silly, and a big waste of time.

I've had to calm down, I have a kid! It is amazing. It's the best thing ever. Nothing better than it.

Wonderful invention, the phonograph. Keeps a man alive long after he's dead.

Silence is safer than speech.

Basically, in 'American Pie,' things are heading in the wrong direction. It is becoming less ideal, less idyllic. I don't know whether you consider that wrong or right, but it is a morality song in a sense.

It's different cultures that make the world go 'round at the end of the day.

If you are an upright journalist, nothing will happen to you.

To grieve is something extremely difficult, we don't even know how to begin to grieve, and I don't know how you can be taught to grieve.

Acting allows me to tell a lot of stories, you know start at the beginning, finish at the end, and tell everything in between. Modelling is just an image.