Symbol Type: Controlling the Method Used to Draw ABP Elements
Symbol type: controlling the method used to draw ABP elements
Three different symbol types are provided for displaying airbag particles giving a trade-off between image quality and rendering speed.
Uses "points" to display particles. These are 2 dimensional squares drawn in the plane of the screen at the appropriate location, and with width and height "radius" x 2.
"Points" are drawn extremely fast in OpenGL, and since a typical airbag may have tens of thousands of particles this is the default display method.
Uses a cube of width, height and depth "radius" x 2 to display particles.
This only ever shows 3 faces, so it is reasonably fast to draw, but it looks a bit odd showing a spherical element as a cube. However cubes have depth and orientation, and can be lit, so the result is better-looking that a "point".
Draws a sphere of the relevant radius, giving a "true" particle appearance. However spheres require many facets for rendering, making these slower to draw.
is a value between 1 and 5 which determines the number of facets used to render the sphere symbols. Each increment halves the equatorial and meridional angular increment size, quadrupling the number of facets on the symbol.
The default value of 1 gives a rather "pointy" looking particle symbol, but it is usually acceptable given their small size. Higher quality values may be necessary when generating images for presentation.
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This image shows a typical "pancake" airbag being inflated by particles. Part of the fabric has been cut away to show the particle elements inside which are drawn by the default "point" method. The three images on the right show a detail of the right hand side to demonstrate how the different display methods appear when enlarged. For this particular analysis the "point" display method gave an animation speed that was limited by the refresh rate of the monitor at 85 frames per second, whereas the "sphere" methods displayed at about 30 fps or slower.
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Default "point" method.
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Spheres, quality = 1
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Spheres, quality = 2
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