Subtitles of the Movie

This movie will cover the use of basic expressions in our composites. A simple formula for calculating values is known as an expression, a word that points to a value is known as a variable. The value stored in the variable may change but the name of the variable has to stay the same. A variable can be something like time or a parameter name or a property. Here are some common variables to use in your expressions; RGBA and Z refer to the values of your original red, green, blue, alpha and Z-values. X and Y are pixel coordinates; width and height refer to the width and height of the image and time refers to the current frame number. And expression can link one parameter to another or combine variables with math and logic type functions to control how a parameter affects a node. It's possible to create animations of parameters using expressions rather than using key frames. Within a node you can link one parameter to another in the following way. There is a shortcut for linking one parameter to another. The way you would do it is by Shift dragging from the name of one parameter to the name of another. When you release the mouse, the link appears; or you can input the name of that parameter by typing in a letter into the text field. For instance here, if I wanted to type in an expression into the Z-center area, I would type in a letter like perhaps time and hit Enter and here, a text expression shows up. When I click the plus, it turns into a minus and expands so I have this text field. And here I can type in the parameter name that I wish to link to. In this case, xcenter and I hit Return to lock it in. Now the values match. To link to a parameter on a different node you must type the name of that node then a period and then the name of the parameter. To alter it further you can use basic math operations like; plus, minus, star or slash, star for multiply, and slash for divide and a number or a different parameter name to create a relationship between three parameters. For instance here, I can do X-center/ and then reference the move2D, which is here. If I just frame that, move2D is the name of it, so xcenter/move2D and then I would press dot and x-center there and hit return. And now this z center parameter has linked together xcenter divided by move2D xcenter and the one from here have all been combined into the z center. To control the order in which our expressions are calculated use parentheses around math functions that should be done together. So I if I want all of this to then be multiplied by 4, I would put a parentheses around all of this and then a star and 4, and when I hit Enter it's valid. If I didn't have a valid expression it turns red, which means that it's an invalid expression. Also, using RND, RND followed by time creates random values based on the variable time as exceed meaning that you'll get randomly generated values in whatever parameter field this is input into. The RND won't work with a static value like a number or a variable that doesn't vary like one of these where they're not animated. When typing in an expression to reference other parameters and nodes it's imperative that you're careful with your spelling and capitalization because otherwise Shake may not recognize what you're trying to say. For instance here, I accidentally capitalized the X in X-center and it turned red, invalid. So if I change that to lowercase it works again. Some nodes are entirely expression driven and for information on these nodes which include the color x, the time x from the other tab, and under the layer tab the layer x. For more information of these nodes, refer to the Shake user manual and it sections on time x which can be found in the adding media, retiming and re-mastering; color x found in the color correction section and layer x which is found in compositing with layer nodes.