CombatHelo Blog (RSS Import)

I cannot take credit for the billboard shader - it was originally in the one of the old mesh.vert files from LE 2.2x. I had originally stated that in my first post but forgot to mention it in the copied version after the previous data loss. But I am glad the post had helped out in any case. BTW, we can't see the images of the results here.

One thing about the billboard shader vertex transformation, it doesn't work to well if you change the camera zoom level (fov).

 

vertexcameraposition = (gl_ModelViewProjectionMatrix * mat[3]) + vec4(gl_Vertex.x,gl_Vertex.z*(buffersize.x/buffersize.y),0.0,0.0);

 

A narrow fov makes the billboards 'shrink', need to fix that. But yes, very helpful post, cheers Mack.

wow that looks very nice Flexman...

Great blog post, Flexman.

It occurs to me, throw imposters into the mix and it's a good basis 3D cloud s. For imposters you just update them if the camera has changed more than a trigger amount.

Haven't come to using particles yet, but this looks great.

Must bookmark this one so I don't forget later on.

is there much, or any, performance hit?

 

--Mike

There is if you use a lot of them. Have them on a reasonably fast recycle time and it's quire reasonable. You get better performance using your own quads instead of a TPlane.

 

This creates a simple two triangle square (like TPlane) and you can move and paint with your billboard material just like a TPlane and it worked out faster for me since I don't need any AABB updates from them. They are typically short duration meshes that are always visible if the parent missile is visible.

 

Every time I create a 'particle' I'm making a quad like this...

 

Self.Sprite = CreateMesh() ;
Self.Surface = CreateSurface(self.Sprite) ;

Local surf:TSurface = Self.Surface;
AddVertex(surf, Vec3(-1, 0, -1)) ;
AddVertex(surf, Vec3(1, 0, 1)) ;
AddVertex(surf, Vec3(1, 0, -1)) ;
AddVertex(surf, Vec3(-1, 0, 1)) ;

AddTriangle(surf, 0, 1, 2) ;
AddTriangle(surf, 3, 1, 0) ;

SetVertexNormal(surf, 0, Vec3(0, 0, -1)) ;
SetVertexNormal(surf, 1, Vec3(0, 0, -1)) ;
SetVertexNormal(surf, 2, Vec3(0, 0, -1)) ;
SetVertexNormal(surf, 3, Vec3(0, 0, -1)) ;

SetVertexTexCoords(surf, 0, Vec2(0, 1)) ;
SetVertexTexCoords(surf, 1, Vec2(1, 0)) ;
SetVertexTexCoords(surf, 2, Vec2(1, 1)) ;
SetVertexTexCoords(surf, 3, Vec2(1, 1)) ;

ScaleMesh(Self.Sprite, vec3(Self.Size)) ;
Self.Sprite.SetPosition(Self.Position) ;

 

I'm using about 100 of these particles. A small loop adds around 10-20 of of different sizes to the tail-pipe of a rocket which moves so fast, blink and you'd miss it. If all the quads shared the same surface it should be as fast as you can probably make it.

 

Updating is done ia pretty small loop in the manager. Particles is a linked list (TList).

 

Method Update()
	For Local p:TParticle = eachin self.Particles
		if p.IsDead
			p.Free() ;
			Self.Particles.Remove(p) ;
		Else
			' UPDATE METHOD FOR EACH PARTICLE '
			p.Update() ;
		End If
	Next
End Method

 

And the update in the TParticle object checks for death and alpha fade....

 

Method Update()
	Local tim:Int = AppTime()
	If tim >= self.Timer Then
		IsDead = True
	Else
		if (tim >= (self.Timer - Self.LifeTime))
			Self.Sprite.SetColorf(self.Color.x, self.Color.y, self.Color.z, ((self.Timer - tim) / Self.LifeTime) * Self.Color.w) ;
		End if
	EndIf
End Method