The Warper


The warper is a powerful tool, that is used to 'warp' or distort areas of an image. The warper operates much like a smear operator, working directly with the 24-bit image data. There are three main oprations of the warper. The simplest operation is the basic warp. The is the basis of all the warper's functions.

Select the warper tool, this allows you to select an area of the image and move the center, distorting the whole area to match. Using the mouse, select the centre of the area you want to warp by pressing and holding down the left mouse button. You can define the area to be affected by the warp by dragging the mouse away from the centre. The area to be affected will be indicated by an ellipse.

When you are happy with the area to warp, release the mouse button. Now you must select a new centre point for the area. The old centre will be dragged to this point, and the whole area stretched to match. Move the mouse around the picture. Guidelines will be drawn from the edge of the circle to the new centre to allow you to judge the position better. When you have decided where you would like to move the middle to, click using the left mouse button (if you decide not to warp, you can click the right mouse button to cancel).

The image will now be warped. If you are not happy with the result you may undo the warp and try again. If you do not have enough memory for an undo buffer, you will not be allowed to do the warp. The warper can also perform two other operations at the same time as

this simple warp. These are selectable from the warper options window, which you can access by clicking on the warper tool icon while it is already selected.

The first option is 'warp facto'. The ranges from -256 to 256. At zero, the warper will do a simple flat warp. At other values the warper will apply a simple perspective effect to the warped image, to make it look more '3D'. For small values this effect will be very subtle. At large values the image will be very distorted. Negative values cause the image to appear as if the centre has been moved backwards 'into' the image. Positive values cause it to be moved forward. You can use the tool to create very distorted images, or to enhance a subtle warp and give it a bit more realism.

The other option you can select, is the 'twirl angl'. This is selectable from -360 to 360 degrees. If you select anything other than zero, the image will be 'twisted'. The centre of the warped area will move through the angle you selected. The farther towards the outside of the area the less it is twisted. The outside of the image will not move at all. This creates a kind of 'whirlpool' effect.

It is important to remember that the twirl effect is done first, followed by the perspective. This means the if you have a very high 'warp factor', the twist will be less obvious, as either the outside or inside of the warped area will be heavily stretched. You should also bear in mind that the warp is a very maths intensive operation, and may take a few seconds to perform on large areas. The warper tool can be both useful, and fun. To get the best out of it, play around and get to know all its features. Try twisting and warping plasmas for some interesting effects. If you get used to how the warper performs in different situations, you will be able to use it more effectively when you really need it.

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