theta.go

package main

import (
    "math"
    "code.google.com/p/go-tour/pic"
)

func Pic(dx, dy int) [][]uint8 {
    pic := make([][]uint8, dy)
    for y := range pic {
        pic[y] = make([]uint8, dx)
        for x := range pic[y] {
            half_dx := float64(dx) / 2
            half_dy := float64(dy) / 2
            _x := (float64(x) - half_dx) / half_dx
            _y := (float64(y) - half_dy) / half_dy
            theta := math.Atan(_x / _y)
            
            pixel := theta / math.Pi
            pic[y][x] = uint8(pixel * 128 + 128)
        }
    }
    return pic
}

func main() {
    pic.Show(Pic)
}