Multithreading

src/ray_marching.go

@@ -6,6 +6,8 @@ package main
 
 import (
 	"math"
+	"runtime"
+	"sync"
 
 	rl "github.com/gen2brain/raylib-go/raylib"
 )
@@ -13,8 +15,8 @@ import (
 const MAX_DIST = 1000.0
 const MAX_STEP = 1000
 const EPS = 0.01
-const WIDTH = 1000
-const HEIGHT = 1000
+const WIDTH = 500
+const HEIGHT = 500
 const PI = math.Pi
 
 const SOFT_SHADOW_COEFF = 32
@@ -102,32 +104,52 @@ func rayMarch(origin Vector3, direction Vector3) (bool, Vector3) {
 }
 
 func genImage() *rl.Image {
-	screenCartesian, _, theta_vec, phi_vec := screenSpherical.SphericalToCartesian()
+	screenCartesian, _, thetaVec, phiVec := screenSpherical.SphericalToCartesian()
 	screenCenter := cameraPos.Add(screenCartesian)
 
 	image := rl.GenImageColor(WIDTH, HEIGHT, rl.Black)
 
-	for pixel_x := range WIDTH {
-		for pixel_y := range HEIGHT {
-			sx := screenPhysicalSize * (float64(pixel_x)/WIDTH - 0.5)
-			sy := screenPhysicalSize * (float64(pixel_y)/WIDTH - 0.5)
+	numWorkers := runtime.NumCPU()
+	var wg sync.WaitGroup
+	wg.Add(numWorkers)
 
-			origin := screenCenter.Add(phi_vec.Scale(-sx)).Add(theta_vec.Scale(sy))
-			direction := (origin.Sub(cameraPos)).Normalized()
+	bandHeight := HEIGHT / numWorkers
 
-			hit, color_vec := rayMarch(origin, direction)
-			var fr, fg, fb float64
-			if hit {
-				fr, fg, fb = color_vec.Unpack()
-			} else {
-				fr, fg, fb = 0, 0, 0
-			}
-			fr, fg, fb = Clamp(fr, 0, 255), Clamp(fg, 0, 255), Clamp(fb, 0, 255)
-			r, g, b := uint8(fr), uint8(fg), uint8(fb)
-			rl.ImageDrawPixel(image, int32(pixel_x), int32(pixel_y), rl.Color{R: r, G: g, B: b, A: 255})
+	for worker := range numWorkers {
+		startY := worker * bandHeight
+		endY := startY + bandHeight
+		if worker == numWorkers-1 {
+			endY = HEIGHT
 		}
+
+		go func(y0, y1 int) {
+			defer wg.Done()
+
+			for pixelY := y0; pixelY < y1; pixelY++ {
+				for pixelX := range WIDTH {
+					sx := screenPhysicalSize * (float64(pixelX)/WIDTH - 0.5)
+					sy := screenPhysicalSize * (float64(pixelY)/HEIGHT - 0.5)
+
+					origin := screenCenter.Add(phiVec.Scale(-sx)).Add(thetaVec.Scale(sy))
+					direction := (origin.Sub(cameraPos)).Normalized()
+
+					hit, colorVec := rayMarch(origin, direction)
+					var fr, fg, fb float64
+					if hit {
+						fr, fg, fb = colorVec.Unpack()
+					} else {
+						fr, fg, fb = 0, 0, 0
+					}
+					fr, fg, fb = Clamp(fr, 0, 255), Clamp(fg, 0, 255), Clamp(fb, 0, 255)
+					r, g, b := uint8(fr), uint8(fg), uint8(fb)
+
+					rl.ImageDrawPixel(image, int32(pixelX), int32(pixelY), rl.Color{R: r, G: g, B: b, A: 255})
+				}
+			}
+		}(startY, endY)
 	}
 
+	wg.Wait()
 	return image
 }