Window to Viewport CS418 Computer Graphics John C. Hart Graphics - - PowerPoint PPT Presentation

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Aug 10, 2023 264 likes •370 views

Window to Viewport CS418 Computer Graphics John C. Hart Graphics Processing Vertex Fragment Scan Converter Shader Shader Window to Viewport Viewport Coordinates (0,VRES-1) (HRES-1,VRES-1) Physical per-pixel integer coordinates

SLIDE 1

Window to Viewport

CS418 Computer Graphics John C. Hart

SLIDE 2

Graphics Processing

Vertex Shader Scan Converter Fragment Shader Window to Viewport

SLIDE 3

Viewport Coordinates

Physical per-pixel

integer coordinates

Also called screen or

device coordinates gl.viewport(x,y,w,h)

x,y – lower left pixel
w – width
h – height
Sometimes (0,0) is in

the upper left corner (e.g. for mouse input)

(0,0) (HRES-1,0) (HRES-1,VRES-1) (0,VRES-1)

SLIDE 4

Window Coordinates

Logical, mathematical

floating-point coordinates

WebGL defaults to a

window extending from (-1,-1) to (1,1)

This is the normalized

coordinate system you would use to plot an equation – Origin at the middle – All four quadrants

(-1,-1) (1,-1) (1,1) (-1,1)

(0,0)

SLIDE 5

Window to Viewport

Translate lower-left

corner of window (-1,-1) to the lower-left corner

f viewport (0,0)

(-1,-1) (1,-1) (1,1) (-1,1)

(0,0)

SLIDE 6

Window to Viewport

Translate lower-left

corner of window (-1,-1) to the lower-left corner

f viewport (0,0)

1 1 1 1 1

(0,0) (2,0) (2,2) (0,2)

(1,1)

SLIDE 7

Window to Viewport

Translate lower-left

corner of window (-1,-1) to the lower-left corner

f viewport (0,0)

1 1 1 1 1

Scale upper-right corner

from (2,2) to upper-right corner of viewport 1

(HRES-1) 2 (VRES-1) 2 (0,0) (HRES-1,0) (HRES-1,VRES-1) (0,VRES-1)

SLIDE 8

Window to Viewport

1 1 1 1 1 1 = 1

(HRES-1) 2 (VRES-1) 2 (HRES-1) 2 (VRES-1) 2 (HRES-1) 2 (VRES-1) 2

SLIDE 9

Graphics Processing

Vertex Shader Scan Converter Fragment Shader 1

(HRES-1) 2 (VRES-1) 2 (HRES-1) 2 (VRES-1) 2