Using Animp to View Animations

Before you use animp you need to prepare a movie file using a particle simulation program which outputs a movie file as described in Writing a Movie File Using C++ or . If you want to try animp on some artificial data execute "mk_movie".

Starting animp

You can start animp either by specifying a movie file on the command line or by simply entering the program name by itself. Under UNIX you might wish to add & to the end of the command to run it in the background.

       animp movie.an &
  

Opening a file

You can click on the File option in the menubar at the top of the screen to open the file menu. From there you can click on the Open option to bring up a file open window. From there you can click on a file and click on Open to open it for animation. You can also double click. If you double click on a file it opens it immediately. Double clicking on a directory name allows you to change to that directory.

Redrawing is suspended while opening a file.

Resizing the window

You can resize the animp window using the the resize corners or the full-screen/normal box in the upper-right section of the title bar. The full-screen/normal box is immediately to the left of the X which kills the program. Some UNIX window managers may not have the X or may resize differently.

To resize with a resize corner, click with the left mouse button on either the lower-right or lower-left corner and hold down the button while moving the mouse. Release the button when the size is as you wish.

The resize function will expand the animation portion of the animp window and retain the width of the controls on the left.

Animp controls

On the left of the animp window is a subwindow containing sliders and buttons which can be used for a variety of tasks. You can control the speed of the animation, change the zoom factor, stop the animation, single step the animation, and exit from the program.

You can also rotate the picture in the right portion of the screen using the left button of the mouse.

Changing the speed

There is a slider labeled "Speed" which you can use to change the rate at which animp switches frames. Slide it to the left to speed up the refresh rate and to the right to slow it down. The leftmost position causes animp to set a timer to expire in 1 microsecond after each frame is displayed. This is effectively as fast as it gets.

Changing the zoom

Below the "Speed" slider is the "Zoom" slider. Its effect is to move the viewing point closer or further away from the center of the animation.

Sliding the Zoom slider to the left moves the viewer closer to the animation. The minimum setting places the viewer in the middle of the animation. The objects will appear much larger and sometimes one object might take up the entire window. Also from this view point the rotation control will not feel natural since the rotation is relative to the center of the animation and you would be viewing object behind the center. They will appear to rotate backwards to what you might expect.

Starting and stopping the animation

There is a button normally labelled "Stop" which can be used to stop the animation. When stopped the label changes to "Start" and can then be used to restart the animation from where it was stopped.

Manually Stepping Through the Frames

Below the start button is the frame counter. It displays the current frame number (starting with 1). You can click on the arrow on the right to step forward 1 frame. After the last frame this will advance to frame 1. You can also click on the double-arrow to advance more quickly through the movie. There are similar arrows on the left of the frame counter to go backwards through the movie.

Changing Colors

Below the frame counter is the color pulldown list. If you click on this button it will show a list of colors. The first is the background which is a sky blue color by default. Following this are the color indices for the objects in the movie. You simply select a color item with the mouse and when you release the mouse button a color changing form will pop up. Move the small square in the color pallette with the mouse to set the color and then move the vertical slider next to the pallette to set the lightness of the color. It is also possible to set numeric values for colors.

If you are happy with your new color click on the OK button and the display will be updated with your new color. If you click on Cancel the colors will remain as before.

Changing the Transparency/Opacity of Objects

Below the color list button is a list button and a slider which you can use to change the opacity (alpha value) of a color. In OpenGL colors have red, green and blue components which define the color itself. They also have an alpha value from 0.0 to 1.0 which can be used to control blending of colors when you draw an object in front of another object. An alpha value of 0.0 would be a completely transparent object. An alpha value of 1.0 would be a completely opaque object. An alpha value of 0.5 would show colors with equal contributions from the old object and the new object.

The list button will have choices like "Trans 0", "Trans 3", etc for each color defined with an alpha value less than 1. After selecting which color to manipulate, you can use the slider to change the alpha value of the color. Sliding to the right makes the object more opaque and sliding to the left makes it more transparent.

Clipping Objects based on Distance

Animp has two counters

Exiting animp

You can exit animp using the X button in the title bar, the "Quit" button in the controls subwindow or the exit option in the File menu. Since animp never writes any files, there will be no questions asked when you exit.

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