func drawScene() {
gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
gl.MatrixMode(gl.MODELVIEW)
gl.LoadIdentity()
gl.Translatef(0, 0, -3.0)
gl.Rotatef(rotationX, 1, 0, 0)
gl.Rotatef(rotationY, 0, 1, 0)
rotationX += 0.5
rotationY += 0.5
gl.BindTexture(gl.TEXTURE_2D, texture)
gl.Color4f(1, 1, 1, 1)
gl.Begin(gl.QUADS)
gl.Normal3f(0, 0, 1)
gl.TexCoord2f(0, 0)
gl.Vertex3f(-1, -1, 1)
gl.TexCoord2f(1, 0)
gl.Vertex3f(1, -1, 1)
gl.TexCoord2f(1, 1)
gl.Vertex3f(1, 1, 1)
gl.TexCoord2f(0, 1)
gl.Vertex3f(-1, 1, 1)
gl.Normal3f(0, 0, -1)
gl.TexCoord2f(1, 0)
gl.Vertex3f(-1, -1, -1)
gl.TexCoord2f(1, 1)
gl.Vertex3f(-1, 1, -1)
gl.TexCoord2f(0, 1)
gl.Vertex3f(1, 1, -1)
gl.TexCoord2f(0, 0)
gl.Vertex3f(1, -1, -1)
gl.Normal3f(0, 1, 0)
gl.TexCoord2f(0, 1)
gl.Vertex3f(-1, 1, -1)
gl.TexCoord2f(0, 0)
gl.Vertex3f(-1, 1, 1)
gl.TexCoord2f(1, 0)
gl.Vertex3f(1, 1, 1)
gl.TexCoord2f(1, 1)
gl.Vertex3f(1, 1, -1)
gl.Normal3f(0, -1, 0)
gl.TexCoord2f(1, 1)
gl.Vertex3f(-1, -1, -1)
gl.TexCoord2f(0, 1)
gl.Vertex3f(1, -1, -1)
gl.TexCoord2f(0, 0)
gl.Vertex3f(1, -1, 1)
gl.TexCoord2f(1, 0)
gl.Vertex3f(-1, -1, 1)
gl.Normal3f(1, 0, 0)
gl.TexCoord2f(1, 0)
gl.Vertex3f(1, -1, -1)
gl.TexCoord2f(1, 1)
gl.Vertex3f(1, 1, -1)
gl.TexCoord2f(0, 1)
gl.Vertex3f(1, 1, 1)
gl.TexCoord2f(0, 0)
gl.Vertex3f(1, -1, 1)
gl.Normal3f(-1, 0, 0)
gl.TexCoord2f(0, 0)
gl.Vertex3f(-1, -1, -1)
gl.TexCoord2f(1, 0)
gl.Vertex3f(-1, -1, 1)
gl.TexCoord2f(1, 1)
gl.Vertex3f(-1, 1, 1)
gl.TexCoord2f(0, 1)
gl.Vertex3f(-1, 1, -1)
gl.End()
}
func (ctx *DrawContext) drawSphere(p vector.V3, r float64, c colorful.Color) {
/* TODO:
- decrease sphere detail if it's further away
- only draw spheres that would be visible inside the frustum:
- (no small spheres near the far plane)
*/
if ctx.cam.SphereInFrustum(p, r) == OUTSIDE {
return
}
gl.Color3f(float32(c.R), float32(c.G), float32(c.B))
gl.MatrixMode(gl.MODELVIEW)
gl.PushMatrix()
defer gl.PopMatrix()
slices := int(math.Max(10, 5*math.Log(r+1)))
gl.Translated(p.X, p.Y, p.Z)
gl.Scaled(r, r, r)
l, ok := uint32(0), false
if ctx.wireframe {
l, ok = ctx.spheresWireframe[slices]
} else {
l, ok = ctx.spheresSolid[slices]
}
if !ok {
ctx.listId++ // XXX: atomic?
l = ctx.listId
gl.NewList(l, gl.COMPILE)
for i := 0; i <= slices; i++ {
lat0 := math.Pi * (-0.5 + float64(i-1)/float64(slices))
z0 := math.Sin(lat0)
zr0 := math.Cos(lat0)
lat1 := math.Pi * (-0.5 + float64(i)/float64(slices))
z1 := math.Sin(lat1)
zr1 := math.Cos(lat1)
if ctx.wireframe {
gl.Begin(gl.LINES)
} else {
gl.Begin(gl.QUAD_STRIP)
}
for j := 0; j <= slices; j++ {
lng := 2 * math.Pi * (float64(j-1) / float64(slices))
x := math.Cos(lng)
y := math.Sin(lng)
gl.Normal3f(float32(x*zr0), float32(y*zr0), float32(z0))
gl.Vertex3f(float32(x*zr0), float32(y*zr0), float32(z0))
gl.Normal3f(float32(x*zr1), float32(y*zr1), float32(z1))
gl.Vertex3f(float32(x*zr1), float32(y*zr1), float32(z1))
}
gl.End()
}
gl.EndList()
if ctx.wireframe {
ctx.spheresWireframe[slices] = l
} else {
ctx.spheresSolid[slices] = l
}
}
gl.CallList(l)
}