# 4 choose a polygon from each side split scene again 5

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Unformatted text preview: ove 4 BSP Tree. 5 5a 1. Choose polygon arbitrarily 2. Divide scene into front (relative to normal) and back half-spaces. 3. Split any polygon lying on both sides. 4. Choose a polygon from each side – split scene again. 5. Recursively divide each side until each node contains only 1 polygon. Lecture 9 5b 2 3 1 4 front 1 2 5a 3 back 4 5b 19/10/2007 * BSP Tree. 5 5a 1. Choose polygon arbitrarily 2. Divide scene into front (relative to normal) and back half-spaces. 3. Split any polygon lying on both sides. 4. Choose a polygon from each side – split scene again. 5. Recursively divide each side until each node contains only 1 polygon. 5b 2 3 1 4 3 front front 5a 2 back 4 5b 1 BSP Tree. 5 5a 5b 2 1. Choose polygon arbitrarily 2. Divide scene into front (relative to normal) and back half-spaces. 3. Split any polygon lying on both sides. 4. Choose a polygon from each side – split scene again. 5. Recursively divide each side until each node contains only 1 polygon. 3 1 4 3 front 2 4 front 5a back 1 5b Displaying a BSP tree. ● BSP tree can be traversed to yield a correct priority list for an arbitrary viewpoint. •Back-to-front : same as painter’s algorithm •Front-to-back : a more efficient approach Lecture 9 19/10/2007 Displaying a BSP tree : Back to Front . ● Start at root polygon. ○ If viewer is in front half-space, draw polygons behind root first, then the root polygon, then polygons in front. ○ If viewer is in back half-space, draw polygons in front of root first, then the root polygon, then polygons behind. ○ If polygon is on edge – either can be used. ○ Recursively descend the tree. ● If eye is in rea...
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