cocos2d for iPhone

A fast, easy to use, free, and community supported 2D game engine

1. 

   Glidos
   Member

   I've spent several weeks fighting with Blender, trying to generate my first properly-constructed game asset. It's been hell, coming new to all this, but I'm starting to get the hang of Blender, and I did eventually construct what I was trying to. Then I was expecting more hell importing it into cocos3d, especially as I have materials with normal maps in the model, but it just worked!! I just... I... What... I... What's going on? I'm not used to this. Things aren't supposed to just work?!

   Ok, that's not quite true: my normal mapped regions came out black on the first go, but I'd already read somewhere that I needed to set up a light tracker, so I just copied how the mash up demo does it, and then it just worked.

   What can I say? Thank you. cocos3d is really quite amazing.

   Posted 5 months ago #
2. 

   davidlxk
   Member

   the title of this thread sounds like Steve Job's catchphrase ~

   Posted 5 months ago #
3. 

   Glidos
   Member

   Actually, I spoke too soon. I just animated the light and the normal map isn't reacting to the changing position. So it very very nearly just works. I'm sure I read something about CC3LightTracker being sensitive to the method use to animate the light, but I can't remember where I saw that now.

   Posted 5 months ago #
4. 

   Glidos
   Member

   I guess the problem is that I don't actually position the light. I rotate a platform on which the light sits. I could do with a way to tell the light tracker that the platform controls the light.

   Posted 5 months ago #
5. 

   Bill Hollings
   Moderator

   @Glidos

   Do you have the shouldTrackTarget property set to YES on the light tracker?

   Have you had a look at the purple head in the CC3DemoMashUp?

   The tracker just sets its globalLightLocation property from the global location of the object it is tracking (the light), so it shouldn't matter if it is on a platform that is moving or not.

   You could also try setting the globalLightLocation property of the light tracker directly.

   ...Bill

   Posted 5 months ago #
6. 

   Glidos
   Member

   Thanks for the reply. That's strange then: it looks like what I have should work
   
CC3Node *lightTrack = [CC3Node nodeWithName:@"LightTrack"];
CCActionInterval *turn = [CC3RotateBy actionWithDuration:5.0 rotateBy:cc3v(0.0, 360.0, 0.0)];
[lightTrack runAction:[CCRepeatForever actionWithAction:turn]];
[self addChild:lightTrack];

   CC3Light* lamp = [CC3Light nodeWithName: @"Lamp"];
   lamp.location = cc3v( -10.0, 10.0, 0.0 );
   lamp.isDirectionalOnly = NO;
   [lightTrack addChild: lamp];

   self.tracker = [CC3LightTracker nodeWithName:@"Tracker"];
self.tracker.shouldTrackTarget = YES;
self.tracker.target = lamp;
[self addChild:self.tracker];

   Elsewhere I add all the actual content to the tracker node. The initial position of the lamp does seem to have an effect on the look of the normal-mapped objects, but nothing changes during the animation.

   Posted 5 months ago #
7. 

   cocojoe
   Member

   Never trust code that works first time ;-)

   Posted 5 months ago #
8. 

   Glidos
   Member

   Aagh! Sorry! It is working. It's just that the effect is rather unimpressive. Looking very carefully, I can now see slight change in the normal-mapped areas, but it's very little. Nothing near what I was seeing in Blender. I guess that's worrying in itself. Is there anything I might have done that would lessen how much response to lighting direction I see in normal mapped areas?

   Posted 5 months ago #
9. 

   Glidos
   Member

   On closer inspection, it looks like I'm getting no specular lighting off the normal-mapped part. Is that a limitation of the system, or might there be a problem with the importing of the material from Blender.

   Posted 5 months ago #
10. 

    Rogs
    Member

    I assume you're expecting to see the bright white spots of specular lighting on on your model.

    However as the texture maps default to modulate blending (i.e. multiply pixel color), anything that is supposed to be white will just be your texture (i.e. diffuse map) map at its brightness.

    From what I've played around, the normal / bump mapping implementation is done by (rough explanation based on what I can understand) calculating the alpha values based on your normal map texture and light coordinates then apply a constant color (which I think defaults to black) with those alpha values on top of your diffuse map to simulate lighting conditions.

    What this means results in, it controls only the intensity of the "dark pixels" of your normal map, but where places are supposed to be white in Blender / 3D Studio, it will appear with no dark pixels.

    -----

    TLDR summary: The normal / bump map implemented only controls "Dark > No lighting" range of pixels, while 3D programs such as Blender / 3D Studio has normal maps control "Dark > No lighting > Bright" range of pixels. That's why you dont see specular lightning of the normal maps.

    You can achieve the similar effect by adding additional code to play around with the texture unit settings but it was tedious when I tried and the effect wasn't as I expected as well when I played around with it.

    This is just based on my observation so people feel free to correct me =)

    Posted 5 months ago #
11. 

    Glidos
    Member

    Thanks Rogs for the info. I think simulating the effect would require more than just changing the texture unit settings, because the specular lighting depends on both camera angle and light angle, whereas the diffuse effect depends only on the light angle. I'd imagine it would require an extra texture unit stage, perhaps using the vector half way between the light and the camera. I guess the stage should do something like

    output-col = input-col + specular-col * hardness-func(dot(normal-map-vect, half-way-vect))

    where half-way-vect is the vector half way between the light and the camera, and hardness-func is a function something like gamma, needed to make the lighting drop off faster when off angle than it does with diffuse lighting. I have no real idea how to actually do it.

    Would be a shame if this isn't possible to do. Specualar lighting makes everything so much more striking.

    I'm still very impressed with how easy it was to get most of the effect I wanted by just running PVRGeoPOD over my Blender model. And specular lighting seems to be working on flat surfaces.

    Posted 5 months ago #
12. 

    Bill Hollings
    Moderator

    @Glidos

    cocos3d supports multiple texture units (that's how the DOT mapping works) via the CC3Material addTexture: method.

    To get some interesting effects (and hopefully the one you want) you can configure the texture unit used by each layered texture by setting and configuring an instance of CC3TextureUnit in the textureUnit property of each CC3Texture you added to the material via the addTexture: method. By default, the texture has no texture unit assigned, and defaults to the standard modulation mentioned above.

    ...Bill

    Posted 5 months ago #

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