// Calculate normals by using cross products along the triangle strips
// and averaging the normals for each vertex
func (terrain *Terrain) CalculateNormals() {
var element_pos uint32 = 0
var AB, AC, cross_product mgl32.Vec3
// Loop through each triangle strip
for x := uint32(0); x < terrain.XSize-1; x++ {
// Loop along the strip
for tri := uint32(0); tri < terrain.ZSize*2-2; tri++ {
// Extract the vertex indices from the element array
v1 := terrain.Indices[element_pos]
v2 := terrain.Indices[element_pos+1]
v3 := terrain.Indices[element_pos+2]
// Define the two vectors for the triangle
AB = terrain.Vertices[v2].Sub(terrain.Vertices[v1])
AC = terrain.Vertices[v3].Sub(terrain.Vertices[v1])
// Calculate the cross product
cross_product = AB.Cross(AC)
// Add this normal to the vertex normal for all three vertices in the triangle
terrain.Normals[v1] = terrain.Normals[v1].Add(cross_product)
terrain.Normals[v2] = terrain.Normals[v2].Add(cross_product)
terrain.Normals[v3] = terrain.Normals[v3].Add(cross_product)
// Move on to the next vertex along the strip
element_pos++
}
// Jump past the lat two element positions to reach the start of the strip
element_pos += 2
}
// Normalise the normals
for v := uint32(0); v < terrain.XSize*terrain.ZSize; v++ {
terrain.Normals[v] = terrain.Normals[v].Normalize()
}
}
func (f *Frustum) SetCamera(p, l, u mgl32.Vec3) {
Z := p.Sub(l)
Z = safeNormalize(Z)
X := u.Cross(Z)
X = safeNormalize(X)
Y := Z.Cross(X)
nc := p.Sub(Z.Mul(f.near))
fc := p.Sub(Z.Mul(f.far))
ntl := nc.Add(Y.Mul(f.nh)).Sub(X.Mul(f.nw))
ntr := nc.Add(Y.Mul(f.nh)).Add(X.Mul(f.nw))
nbl := nc.Sub(Y.Mul(f.nh)).Sub(X.Mul(f.nw))
nbr := nc.Sub(Y.Mul(f.nh)).Add(X.Mul(f.nw))
ftl := fc.Add(Y.Mul(f.fh)).Sub(X.Mul(f.fw))
ftr := fc.Add(Y.Mul(f.fh)).Add(X.Mul(f.fw))
fbl := fc.Sub(Y.Mul(f.fh)).Sub(X.Mul(f.fw))
fbr := fc.Sub(Y.Mul(f.fh)).Add(X.Mul(f.fw))
const (
top = iota
bottom
left
right
nearP
farP
)
f.planes[top].setPoints(ntr, ntl, ftl)
f.planes[bottom].setPoints(nbl, nbr, fbr)
f.planes[left].setPoints(ntl, nbl, fbl)
f.planes[right].setPoints(nbr, ntr, fbr)
f.planes[nearP].setPoints(ntl, ntr, nbr)
f.planes[farP].setPoints(ftr, ftl, fbl)
}
// Since go has multiple return values, I just went ahead and made it return the view and perspective matrices (in that order) rather than messing with getter methods
func (c *Camera) ComputeViewPerspective() (mgl32.Mat4, mgl32.Mat4) {
if mgl64.FloatEqual(-1.0, c.time) {
c.time = glfw.GetTime()
}
currTime := glfw.GetTime()
deltaT := currTime - c.time
xPos, yPos := c.window.GetCursorPosition()
c.window.SetCursorPosition(width/2.0, height/2.0)
c.hAngle += mouseSpeed * ((width / 2.0) - float64(xPos))
c.vAngle += mouseSpeed * ((height / 2.0) - float64(yPos))
dir := mgl32.Vec3{
float32(math.Cos(c.vAngle) * math.Sin(c.hAngle)),
float32(math.Sin(c.vAngle)),
float32(math.Cos(c.vAngle) * math.Cos(c.hAngle))}
right := mgl32.Vec3{
float32(math.Sin(c.hAngle - math.Pi/2.0)),
0.0,
float32(math.Cos(c.hAngle - math.Pi/2.0))}
up := right.Cross(dir)
if c.window.GetKey(glfw.KeyUp) == glfw.Press || c.window.GetKey('W') == glfw.Press {
c.pos = c.pos.Add(dir.Mul(float32(deltaT * speed)))
}
if c.window.GetKey(glfw.KeyDown) == glfw.Press || c.window.GetKey('S') == glfw.Press {
c.pos = c.pos.Sub(dir.Mul(float32(deltaT * speed)))
}
if c.window.GetKey(glfw.KeyRight) == glfw.Press || c.window.GetKey('D') == glfw.Press {
c.pos = c.pos.Add(right.Mul(float32(deltaT * speed)))
}
if c.window.GetKey(glfw.KeyLeft) == glfw.Press || c.window.GetKey('A') == glfw.Press {
c.pos = c.pos.Sub(right.Mul(float32(deltaT * speed)))
}
// Adding to the original tutorial, Space goes up
if c.window.GetKey(glfw.KeySpace) == glfw.Press {
c.pos = c.pos.Add(up.Mul(float32(deltaT * speed)))
}
// Adding to the original tutorial, left control goes down
if c.window.GetKey(glfw.KeyLeftControl) == glfw.Press {
c.pos = c.pos.Sub(up.Mul(float32(deltaT * speed)))
}
fov := initialFOV //- 5.0*float64(glfw.MouseWheel())
proj := mgl32.Perspective(float32(fov), 4.0/3.0, 0.1, 100.0)
view := mgl32.LookAtV(c.pos, c.pos.Add(dir), up)
c.time = currTime
return view, proj
}