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Glints

Glints are a simple (if cliched) way to add interest to an image, along with lens-flare effects, sparkles and highlights. Here we'll define a new brush to add glints to the metallic object created in the previous section.

• We need a basic star shape for the brush. You can do this with the drawing set in Photodesk, but it's much easier in Draw or ArtWorks. I made the one below in Artworks; you can download it as a zipped Draw file, or create your own if you want.

  

  The basic star shape

• Create a new image in Photodesk. The Texture preset is about the right size.
• Drag your brush (unzipping it first if you're using the download) into the image window. A window will open with various rendering options. Set it up as below:

  

  Loading the Draw brush

• Click on Render, and the star will be drawn onto the canvas, nicely anti-aliased (unlike the preview shown here). Fix.
• Open the Airbrush window and expand it to full size (top right button on the title bar, or select Design... from the window's menu).
• Select Sample from the Airbrush window menu:

  

  Setting up the sample operation

• When you move the mouse pointer over the star image it will change to a syringe. Now click carefully over a black part of the star, and it should appear in the brush pane:

  

  Sampling the brush

• If you get it wrong, try holding down the Alt key and dragging out a box surrounding the star.
• Increase the Spacing parameter to 100% (the maximum) and click on Add to set. The brush will now appear in the selection window (scroll it down to see it). Use the Find... and Save menu options if you want to save your new brush for future use.
• A word of warning:> I've had various inexplicable crashes while sampling brushes. Often it works fine, but sometimes I get "Unexpected error" boxes, or the machine freezes. Save any work first.
• Now we'll use the new brush. Open the wrench image you created in the previous section, and select the glint brush in the Airbrush window.
• Open the Palette window and select white, and apply to appropriate bits of the image. Adjust the density if it's too bright. If you just get a solid blob of white, check that Stream is switched off in the Airbrush tool styling window (click on the bluish textured icon on the toolbar). Inadvertant texturising can also lead to mystifying effects (same window).
• Add a haze round each star for a further pleasing effect. To do this, select the large circular airbrush (the first one in the window), open its Gradient window and move the little blue squares until you get a black central dot surrounded by faint grey, as below. Increase the size of the brush if you like.

  

  Adding a nimbus

• Click on a star, repeating if you like to build up a nimbus. And here's the final result:

  

  The star bangled spanner

Notes

• At the size used here and below, the anti-aliasing done when you import the drawing gives a softish edge to the star, but if you make any larger ones apply a small (1-2 pixels) gaussian blur before sampling it.
• I've made a file with a selection of different-sized glint brushes, which you can get from the downloads page.
• If you want proper glints and lens flares you should look at the Persistence of Vision ray tracer (version 3.10g has been ported to RISC OS by Jérôme Mathevet, and I believe someone else is working on a more recent version). Various people have written programs for it which accurately simulate the effect. Cerilica's Insignia effects program will also add simple lens flares.