GAMES101-05光栅化1(三角)

一、Rasterization 1 (Triangles)

vertical field-of-view (fovY) andaspect ratio
长宽比和垂直的可视角度

How to convert from fovY and aspect to l,r, b, t?Trivial

What’s after MVP?
将物体锁定在（-1，1）^3的立方体内
Canonical Cube to Screen
What is a screen?

• An array of pixels
• Size of the array: resolution
• A typical kind of raster display
  Raster == screen in German
• Rasterize == drawing onto the screen
  Pixel (FYl, short for “picture element”)
• For now: A pixel is a little square with uniform color
• Color is a mixture of (red, green, blue)
  
  以屏幕的左下角为原点开始确定坐标。
  Pixels’ indices are in the form of (x, y)., where both x and y are integers
  Pixels" indices are from(0, 0) to (width - 1, height - 1)
  Pixel (x, y) is centered at(+0.5,y+0.5)

将宽高由（-1，1）拉长w，h

Drawing Machines
Laser Cutters
Different Raster Displays
Oscilloscope 示波器
Cathode Ray Tube 阴极射线管

隔行扫描，短暂的视觉暂留。高速运动时会产生严重的画面撕裂。
Frame Buffer: Memory for a Raster Display
内存的区域映射到屏幕上
Flat Panel Displays
LCD(iiquid Crystal Display)Pixel 液晶

光经过光栅只会留下在这个方向震动的波
通过光栅液晶的扭曲得到目标角度的光线。
LED Array Display 发光二极管
electropnoretic (Electronic lnk) Display 电子墨 kindle

• Drawing to Raster Displays*
  Triangle Meshes表示二位空间
  Triangles - Fundamental Shape Primitives：

• Most basic polygon
• Break up other polygons
  Unique properties
• Guaranteed to be planar
• Well-defined interior
• Well-defined method for interpolating values atvertices over triangle (barycentric interpolation)

A Simple Approach: Sampling采样
Samping a Function
Evaluating a function at a point is sampling.we can discretize a function by sampling.将函数离散化
以中心点采样

for (int x = 0; x < xmax; ++x)
for (int y=0; y <ymax; ++y)
image [x][y] = inside (tri,
+0. 5,y + 0.5) ;

p1p2*p1q朝外，在p1p2左侧
经过三次判断确定在以上那个区域内
若点在三角形边界上如何判定由自己觉定。

轴向包围盒
各种神奇的加速方法

Rasterization on Real Displays

bayer parten 绿色的点更多，因为人眼对绿色更为舒服


==Jaggies!==Aliasing
抗锯齿，防走样