Oops, sucking

tinyrender2/main.go

@@ -12,7 +12,7 @@ const (
 	Width      = 512
 	Height     = 512
 	ObjectFile = "head.obj"
-	Repeat     = 100_000
+	Repeat     = 1 //00_000
 )
 
 func must(err error) {

tinyrender2/render.go

@@ -44,8 +44,63 @@ func line(fb *Framebuffer, color uint, v0 Vec2i, v1 Vec2i) {
 	Bresenham2(fb, color, v0.X, v0.Y, v1.X, v1.Y)
 }
 
+/*func LineSweep(fb *Framebuffer, color uint, v0 Vec2i, v1 Vec2i, v2 Vec2i) {
+
+}*/
+
 func Triangle1(fb *Framebuffer, color uint, v0 Vec2i, v1 Vec2i, v2 Vec2i) {
-	line(fb, color, v0, v1)
+	// Very silly manual sorting by Y
-	line(fb, color, v1, v2)
+	if v2.Y < v0.Y {
-	line(fb, color, v2, v0)
+		v0, v2 = v2, v0
+	}
+	if v1.Y < v0.Y {
+		v0, v1 = v1, v0
+	}
+	if v2.Y < v1.Y {
+		v1, v2 = v2, v1
+	}
+
+	// The lesson says to always figure out what's on the left.
+	// As such, we always go from left to right
+	// While drawing the straight line, go the opposite direction if the
+	// longer side is on the right (we go from long side to short)
+	var sweep int = 1
+	if v2.X > v1.X {
+		sweep = -1
+	}
+
+	// Don't worry about speed for now...
+	dy := float32(v2.Y-v0.Y) - 0.5
+	var v02step, v01step, v12step, xlong, xshort float32
+
+	xlong = float32(v0.X) + 0.5
+	xshort = xlong
+
+	// We can check just for greater than because we sorted the vertices
+	if dy > 0 {
+		v02step = (float32(v2.X-v0.X) - 0.5) / dy // long side always
+		v01step = (float32(v1.X-v0.X) - 0.5) / dy // first short side
+		v12step = (float32(v2.X-v1.X) - 0.5) / dy // second short side
+		xshort += v01step / 2
+		xlong += v02step / 2
+	} else {
+
+	}
+
+	for y := v0.Y; y <= v2.Y; y++ {
+		// Draw a horizontal line from
+		for x := int(math.Floor(float64(xlong))); x <= int(math.Floor(float64(xshort))); x += sweep {
+			fb.SetSafe(uint(x), uint(y), color)
+		}
+		xlong += v02step
+		if y < v1.Y {
+			xshort += v01step
+		} else {
+			xshort += v12step
+		}
+	}
+
+	// line(fb, color, v0, v1)
+	// line(fb, color, v1, v2)
+	// line(fb, color, v2, v0)
 }