Gimp Tutorial: Crystal Ball
Create a "Crystal Ball" effect with The Gimp.
This tutorial is my interpretation of the following (dutch) page, http://www.bartendavid.be/doc/howto/multimedia/gimp/crystalbal.shtml. I am currently using Gimp 2.0pre3 installed from tarball (on Mandrake 10 Test-something) for this.
1. Create a new image of 400 x 400 pixels, select "RGB" for Image Type, and "Transparent" for Fill Type. Using the ellipse tool, draw the outer circle. Press shift while dragging to make the elipse tool draw a circle.
2. Create a new transparent layer called "Ring". Select the gradient tool. In the tool options window, select "FG to BG" in the Gradient dropdown and "Radial" in the Shape dropdown. Change the foreground colour to a light blue (#8FBEE8), and the background colour to black (#000000). Drag the mouse from the upper left section of the circle to the lower right. You should now have a gradient filled circle, and the selection should still be active.
3. Using Select->Shrink from the menu, shrink the selection by 9 Pixels. Press Ctrl+K to clear the selection. The centre of the circle should now be transparent.
4. Using Select->Grow, grow the selection by 2 pixels. Create a new transparent layer called "Circle". Make sure this layer is between the Background layer and the Ring layer. Change the foreground colour to #A3DB1D, and select the bucket tool. In the tool options window, change the "Affected Area" to "Fill Whole Selection".
5. Create a new transparent layer called "Shade". Drag over one vertical and one horizontal guide and centre them within the circle. (You may need to toggle the guides on to see them (press Ctrl+Shift+T). Make sure the "Shade" layer sits between the "Circle" layer and the "Ring" layer. Choose the eliptical selection tool, and in the tool options window, select "Feather Edges", and change "Radius" to 30. Using the Ctrl key (to subtract the next selection from the current selection), draw a circle, like the selected one, but starting slightly off-centre, to the right of the guide centre-points. This should leave a sickle-shaped selection on the left side of the inner circle.
6. Making sure the "Shade" layer is active, and the sickle shape in the left looks good, select the bucket tool (Shift+B), black as a foreground colour, and then fill the selection. It should be feathered on the inside nicely if the inner selection was done properly. Change the opacity of this layer to 30%.
7. Select the "Circle" layer. In the "Layer->Transparency" menu, select "Alpha to Selection". Select the "Shade" layer again. This should select the inner circle. Select the eliptical selection tool again, with the feathering set to 100 this time. Create another sickle, like the previous one, but make it hug the top of the circle, not the left, make it thicker too. Ctrl+Click on the centre line near the very bottom of the circle, and drag upwards and outwards until you get the right shape. Select the bucket tool and black for the foreground colour, and fill the selection. Again, if the feathering was set correctly, it should be nicely blurred on the inside edge.
8. Create a transparent layer called "Highlight" and move it to the top of the stack. Using the ellipse tool, create a wide ellipse that takes up most of the top half of the inner circle. Select white as the foreground colour. Then select the gradient tool, and in the tool options window, change Gradient to "FG to Transparent" and Shape to "Linear". Drag from just below the top of the new ellipse, to just above the bottom of the ellipse. Change the transparency of this layer to 80%.
9. For this example, we're just going to insert some text, but anything smaller than the outer ring would work equally well. Select the text tool, and type something in. Increase the size to fill the inner circle. Make sure the text layer is positioned between somewhere between the "Shade" and "Highlight" layers.
10. Select the "Ring" layer. Choose Script-Fu->Shadow->Drop-Shadow. Set both offsets to 4. Move the "Drop-Shadow" layer almost to the bottom of the stack, but leave the Background layer at the very bottom. Select the background layer and fill with white. If you prefer, you can also change the transparency of the text layer to something around 25%.
