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!

.

I see myself as a mom first. I'm so lucky to have that role in life. The world can like me, hate me, or fall apart around me and at least I wake up with my kids and I'm happy.

I still feel like my best surfing is ahead of me.

I am delighted, excited, and deeply honored.

We don't always choose moments. You know, sometimes they choose us.

All my ego wants is to be sitting by a lake in Italy. It doesn't want to be backstage, warming up.

I find inspiration in everything.

Don't ask me who my favourite monster was because I'm sick of saying Tom Baker.

When people are around us, they should leave better off than they were previously. Rather than feeling discouraged or defeated, people should feel challenged and inspired after spending any time with you and me.

I am very old-fashioned about marriage. It is for life and I mean it. I always knew that when I met the right girl, the life I had before - being single, in a band, girls everywhere - would be over.

I'm not going to play my violin, but with my dwarfism, I'm a bit of a mutant.

I don't have a day job, so I read any time of day.

There's no doubt my having been a ballplayer made me feel a special sense of responsibility to Joe Jackson's life.

I am plenty lonely in hotel rooms.

I'm a great believer in the novelist being 'on the scene,' reporting, traveling, meeting all sorts of people.

The day is not far off when the economic problem will take the back seat where it belongs, and the arena of the heart and the head will be occupied or reoccupied, by our real problems - the problems of life and of human relations, of creation and behavior and religion.

My work is a self-portrait of my mind, a prism of my convictions.

I don't do stunts and I don't think many actors do. For an actor to say they do their own stunts I don't think is very respectful of the profession of stunt men and women.

I can't stand when people say, 'Don't hate me because I'm beautiful'. OK, how about I hate you because you said that.

I've been cycling ever since I was a kid. I remember taking my cycling proficiency test aged seven - I got to school at 7:30 A.M. to practise, I was so nervous. After that, I always cycled to school.

This line of research continued when I went, and brought my research group with me, to the new University of California, Irvine campus in 1966 to become the founding Dean of the School of Physical Sciences.

I am for our not having any discrimination in tax legislation.

People who've had very unhappy childhoods are pretty good at inventing themselves. If nobody invents you for yourself, nothing is left but to invent yourself for others.

I honestly don't know, but if America continues to refuse to reduce its greenhouse gas emissions, I see a bleak future not only for American society, but for the world as a whole. This is a global problem that is not going away, and the United States is an obstacle to solving it.

I wish everyone was a sci-fi geek because then there would be no violence in the world. There'd be no wars. There'd only be people e-mailing each other.