Before GL_ARB_multisample extension, the edges of lines, polygons, and points could be selectively antialiased using using glEnable(GL_LINE_SMOOTH), glEnable(GL_POLYGON_SMOOTH), glEnable(GL_POINT_SMOOTH) respectively, combined with a blending function, such as glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA). Such features were typically not implemented in hardware in early consumer graphics cards at the time, and were done in software resulting in poor performance. More expensive "workstation" graphics cards from HP, Sun, and SGI at the time did implement these features in hardware. Modern programs should not make use of these features.

1. Sampling and Aliasing
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2. Introduction
• In computer graphics, we use the term “aliasing” but where does it
come from?
• Sampling theory explains where these errors arise and what we
might do to avoid them
• Explains both digitization and display
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3. Sampling Process
• Measure f(x,y) on grid
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4. Ambiguity from Samples
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5. Basis Images
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6. Sampling and Replication
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7. Replication with Overlap
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8. Aliasing
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10. Sampling
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point sampling area sampling

11. Sinc function
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12. Reconstruction with Sinc
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13. Two dimensional sinc
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14. Point Spread of CRT Beam
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15. Reconstruction functions
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sinc rectangle triangle Gaussian

16. Quantizer
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