2d game rendering with ogre

murderv · Post by **murderv** » Wed Jul 18, 2007 3:26 pm

hi there,
i dont know if any of you tried the OgreMagic addon for Ogre (http://www.freewebs.com/ogremagic/). i havent but i took a look at it.

aside my reasons why to code a 2d game using ogre, i wanted to know how could i port this code for opengl ?

for what i've seen OgreMagic draws everything using D3D device directly, it gets the d3ddevice from Ogre and from there it does it's own rendering..

i havent seen anything on how i could do this to be able to render using opengl calls..

anyone have any idea? if there a port of this already ?

[EDIT]
i forgot. would it be a good idea or an easier-to-implement way to use ManualObjects to create a 2d rendering system on top of ogre?
[/EDIT]

PS. my needs are static & animated sprites, also the timeline is a useful thing

eugen · Post by **eugen** » Wed Jul 18, 2007 5:43 pm

i have no knowledge of OgreMagic but why would the owner code it for D3D when all specific render operations are abstracted?!
Are u sure it doesnt work with opengl also?

hmoraldo · Post by **hmoraldo** » Wed Jul 18, 2007 6:27 pm

Check the SpriteManager2d code in the wiki: http://www.ogre3d.org/wiki/index.php/SpriteManager2d. You might get some idea of how to do 2d rendering that is not dependant of a specific render system.

murderv · Post by **murderv** » Wed Jul 18, 2007 6:46 pm

eugen, yes im pretty sure, he gets the d3d device and does d3d calls himself..

hmoraldo, hey. ive found that too, i was going thru it this afternoon. it only supports static sprites right ?

i have a couple of question regarding this subject, but i have to leave now.. ill post tomorrow..

thanks guys

hmoraldo · Post by **hmoraldo** » Wed Jul 18, 2007 7:03 pm

What do you mean by static sprites? You can animate them, move them, etc, just as you'd do if you'd blitted them with the good old DirectDraw. They are not static in the sense overlays are, if that's your question.

murderv · Post by **murderv** » Thu Jul 19, 2007 10:28 am

moraldo, i have just noticed you can feed texture coordinates to the method parameters.. so i should just make a animatedSprite class around this and based on some speed draw different parts of the texture.. would that be the correct way to do it?

another question i have is what about raycasting.. how could i pick any sprite and drag it around the screen?

ive noticed you use relative coordinate system (0,0) is center of the screen.. shouldnt be hard to chagne that to put (0,0) as top-left corner.

one other question moraldo, what about using materials instead of textures? or even use manualobjects? any advantages over this one ?

[EDIT]
what about colorkey masking or transparency? whats the best way to handle it for sprites?
[/EDIT]

thanks

hmoraldo · Post by **hmoraldo** » Fri Jul 20, 2007 3:38 pm

murderv wrote:moraldo, i have just noticed you can feed texture coordinates to the method parameters.. so i should just make a animatedSprite class around this and based on some speed draw different parts of the texture.. would that be the correct way to do it?

Yes, you can just make animated sprites by feeding the sprite manager with different textures or different parts of a texture so that to the user, a different image is shown at every instant. Also you can displace the sprites by changing their destination coordinates.

All you see in sprite based games, you can do by using this kind of methods. It basically depends on your ingenuity.

murderv wrote:another question i have is what about raycasting.. how could i pick any sprite and drag it around the screen?

Well, the sprite manager isn't prepared for that directly. You can program that by checking what sprite is below the cursor, always checking the cursor isn't pointing to a transparent pixel of course.

murderv wrote:ive noticed you use relative coordinate system (0,0) is center of the screen.. shouldnt be hard to chagne that to put (0,0) as top-left corner.

Not at all, that would be easy, as that kind of change of coordinates only requires using an addition over the coordinate components (x+somevalue, y+somevalue). Sorry I have no time now to send you a patch, but it would be actually easy to implement.

murderv wrote:one other question moraldo, what about using materials instead of textures? or even use manualobjects? any advantages over this one ?

It's just using textures for simplicity and efficiency.

murderv wrote:what about colorkey masking or transparency? whats the best way to handle it for sprites?

Use pngs with transparency channel, Ogre will take care by itself (they will be loaded as sprites with transparency automatically)

I'll copy this to the sprite manager thread...

Best regards!

murderv · Post by **murderv** » Mon Jul 23, 2007 3:55 pm

hmoraldo,

i updated the sprite hanlder class to load and work with animated sprite sheets, but i do have one other question.

how about working with transformed (scaling & rotation) sprites ?

im not sure how to fit this with the sprite element and transforming them locally.

[eDIT]
rotations should be only around z-axis. no need for others.
about scaling it should be uniform. scales to all sides by same amount
[/EDIT]

any idea ?

thanks in advance

hmoraldo · Post by **hmoraldo** » Mon Jul 23, 2007 5:31 pm

To do that you'll need to further modify the code. Read the 2d sprite manager code and try to understand the way it works, you'll see the change you propose is no very hard to do (though you'll need some basic maths for the orientation stuff).

murderv · Post by **murderv** » Mon Jul 23, 2007 5:51 pm

ive been doing that, experimenting to scale it and working out the orientation part..

as the sprites are aligned by the top left corner the scaling isnt working as i wanted.. it stretches down right. i should create the sprite shapes with its align in the center.. i think that should give me the correct scaling.

about the orientation, here's what i've added

Ogre::Matrix4 rotMat;
Ogre::Quaternion quat;
Ogre::Vector3 dir = Ogre::Vector3::UNIT_Z;
quat.FromAngleAxis( Ogre::Radian(_scale), dir );
rotMat.makeTransform( Ogre::Vector3::ZERO, Ogre::Vector3::UNIT_SCALE, quat );
pos1 = rotMat * pos1;
spriteElement.x1 = pos1.x;
spriteElement.y1 = pos1.y;
rotMat.makeTransform( Ogre::Vector3::ZERO, Ogre::Vector3::UNIT_SCALE, quat );
pos2 = rotMat * pos2;
spriteElement.x2 = pos2.x;
spriteElement.y2 = pos2.y;

its an hack that rotates the rect points but it rotates then shape around the "world" origin and not around the shape center or even shape's pivot point. if anyone have a good idea on how to work this out..

murderv · Post by **murderv** » Tue Jul 24, 2007 12:40 pm

i have modified the spritehandler class to support sprite animation aswell as scaling + rotations..
if anyone is interested let me know. i can put the code available to everyone..
cheers for the community and support

hmoraldo · Post by **hmoraldo** » Tue Jul 24, 2007 2:19 pm

murderv wrote:i have modified the spritehandler class to support sprite animation aswell as scaling + rotations..
if anyone is interested let me know. i can put the code available to everyone..
cheers for the community and support

Maybe you can do as the author of OgreSprites did: he posted his changes in the wiki, in a separate page of the original SpriteManager2d (so to keep the original one simple and easy to modify). OgreSprites is here: http://www.ogre3d.org/wiki/index.php/OgreSprites and the SpriteManager2d here: http://www.ogre3d.org/wiki/index.php/SpriteManager2d.

Best regards and thanks for using this code!

murderv · Post by **murderv** » Tue Jul 24, 2007 3:01 pm

im based on top of the OgreSprites namespace. all i did was change it to handle some more stuff. should i create a new one anyway ?

hmoraldo · Post by **hmoraldo** » Tue Jul 24, 2007 3:50 pm

murderv wrote:im based on top of the OgreSprites namespace. all i did was change it to handle some more stuff. should i create a new one anyway ?

Hmmm... you should contact his author and ask him what he does prefer. I suppose having only two versions (a simple Sprite Manager and an enhanced one) would be better than having a lot of them. But I guess this should be his choice after all.

murderv · Post by **murderv** » Tue Jul 24, 2007 3:51 pm

will do. thank you moraldo!

hmoraldo · Post by **hmoraldo** » Tue Jul 24, 2007 4:30 pm

No problem, thank you for using the manager...

digitalgibs · Post by **digitalgibs** » Mon Aug 23, 2010 10:36 pm

http://www.ogre3d.org/tikiwiki/SpriteManager2d doesn't work for me. I got it to compile but it renders nothing, despite going through the render calls. Using Ogre 1.7.

[edit] It is rendering shadows into the world, so if there is a shadow casting light it will clear the sprite list after the shadow pass. Is there a way around this?

Lax · Post by **Lax** » Sun Jan 03, 2016 3:49 pm

Hi digitalgibs,

did you solve your issue with spritemanager2d and shadows? I'm encountering the same problem and don't have a hint how to solve this. Ass soon as shadows are enabled I see no background sprite

Regards,
Lax

Bernardtot · Post by **Bernardtot** » Tue Jan 12, 2016 8:46 pm

how would i start a game of spring? would i do it with spring lobby or spring exe.?

Ogre Forums