Working frame generation

.gitignore

@@ -4,3 +4,4 @@
 *.gif
 *.jpg
 *.jpeg
+a.out

go1/main.go

@@ -3,12 +3,56 @@ package main
 import (
 	"fmt"
 	"github.com/ungerik/go3d/vec3"
+	"log"
+	"strings"
+	"time"
 )
 
-func main() {
-	fmt.Printf("Hello world")
-	thing := vec3.T{
-		0, 0, 0,
-	}
-	fmt.Printf("Thing: %v", thing)
+// 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")
 }