package main

import (
	"fmt"
	"github.com/ungerik/go3d/vec3"
	"log"
	"strings"
	"time"
)

// Clamp a float value to the given range
func fclamp(val float32, minval int, maxval int) int {
	return max(minval, min(maxval, int(val)))
}

func main() {
	log.Printf("Program begin")
	const (
		width  = 1024
		height = 768
		colmax = 255
	)
	framebuffer := make([]vec3.T, width*height)

	now := time.Now()
	for y := range height {
		for x := range width {
			framebuffer[x+y*width] = vec3.T{
				float32(y) / float32(height),
				float32(x) / float32(width),
				0,
			}
		}
	}
	log.Printf("Generate frame took %dms", time.Since(now).Milliseconds())

	fmt.Printf("P3\n%d %d\n%d\n# Image contents\n", width, height, colmax)

	var buffer strings.Builder
	now = time.Now()

	for i := range height * width {
		fb := framebuffer[i]
		buffer.WriteString(fmt.Sprintf("%d %d %d\t",
			fclamp(colmax*fb[0], 0, colmax),
			fclamp(colmax*fb[1], 0, colmax),
			fclamp(colmax*fb[2], 0, colmax),
		))
		if i&63 == 63 {
			buffer.WriteRune('\n')
		}
	}

	log.Printf("Conversion took %dms", time.Since(now).Milliseconds())

	fmt.Printf(buffer.String())
	fmt.Printf("\n# Image end\n")
}