Ship trails

Hi all,

For a ship simulator type of game, how do I create realistic ship trails?

Regards,
Cg

Maybe this nice hack is what you are looking for: http://www.ogre3d.org/forums/viewtopic.php?f=1&t=47645

xad

Maybe this nice hack is what you are looking for: http://www.ogre3d.org/forums/viewtopic.php?f=1&t=47645

xad

Hi xad,

This is my first attempt http://www.youtube.com/watch?v=-Usp7KZvZq8 to create the water wake using the wake.png texture from http://www.ogre3d.org/forums/viewtopic.php?f=1&t=47645, any idea on how to improve the water wake? Below is my particle file:


particle_system Water/Wake
{
quota 220
material Water/Wake
particle_width 1.5
particle_height 1.5
cull_each true
renderer billboard
billboard_type point

emitter Box
{
angle 0
colour 1 1 1 1
colour_range_start 1 1 1 1
colour_range_end 1 1 1 0
direction 0 1 0
emission_rate 10
position 0 0.2 0
velocity_min 0.0
velocity_max 0.4
time_to_live_min 5
time_to_live_max 7
duration 0
duration_min 0
duration_max 0
repeat_delay 0
repeat_delay_min 0
repeat_delay_max 0
width 2
height 2
depth 1
}

affector Scaler
{
rate 0.6
}

affector ColourFader2
{
red1 0
green1 0
blue1 0
alpha1 0
red2 0
green2 0
blue2 0
alpha2 -1
state_change 1
}
}


and my material file:


material Water/Wake
{
technique
{
pass
{
lighting off
scene_blend alpha_blend
depth_write off

texture_unit
{
texture wake.png
}
}
}
}



Thanks,
CG

dont you have to create a "sphere" mesh instead of a particle system?

The simplest way to create ships trails with Hydrax is to use Hydrax's DecalManager. I have not actually got round to doing this yet so i cant tell you exactly what to do but will get round to it soon.

Angus

Maybe render Ship trails with decals can be a little slow, because each decal needs a new pass in the Hydrax material, so.. if with a good particle system script you're able to get a realistic ship trail, it'll be fine!

Xavi

P.D.: Decals are useful to render needed things over the water, because with 20/30 on the water the frame frop could be 10/15fps, and it's not very good..., so I suggets avoid decals to details, and use them only if they are really needed!

Maybe render Ship trails with decals can be a little slow, because each decal needs a new pass in the Hydrax material, so.. if with a good particle system script you're able to get a realistic ship trail, it'll be fine!

Xavi

P.D.: Decals are useful to render needed things over the water, because with 20/30 on the water the frame frop could be 10/15fps, and it's not very good..., so I suggets avoid decals to details, and use them only if they are really needed!

Hi Xavi,

How do I remove the blue background of the particle image as depicted in the screen shot?

[attachment=0]particle.jpg[/attachment]

I've added the particle material to Hydrax using


mHydrax->getMaterialManager()->addDepthTechnique(
static_cast<Ogre::MaterialPtr>(Ogre::MaterialManager::getSingleton().getByName("Water/Wake"))->createTechnique());


but the blue background is still there. Below is my particle material:


material Water/Wake
{
technique
{
pass
{
lighting off
scene_blend alpha_blend
depth_write off

texture_unit
{
texture smoke.png
}
}
}
}


and particle script:


particle_system Water/Wake
{
quota 500
material Water/Wake
particle_width 30
particle_height 30
cull_each false
renderer billboard
billboard_type perpendicular_common
common_direction 0 1 0
common_up_vector 0 0 1

emitter Point
{
angle 0
colour 1 1 1 1
direction -1 0 0
emission_rate 10
position 0 0 0
velocity_min 0.0
velocity_max 1
time_to_live_min 4
time_to_live_max 4
duration 0
duration_min 0
duration_max 0
repeat_delay 0
repeat_delay_min 0
repeat_delay_max 0
width 10
height 20
//depth 10
}

affector Scaler
{
rate 0.6
}

affector ColourFader2
{
red1 0
green1 0
blue1 0
alpha1 0
red2 0
green2 0
blue2 0
alpha2 -1
state_change 1
}
}


I'm using the smoke texture from the samples folder and using alpha_blend.

Thanks,
CG

I think the best way is to use a custom Hydrax depth technique, just add in your particle material a new technique with "HydraxDepth" scheme name and a transparent colour pass, so the particles won't be visible for the Depth RTT, and you'll get the effect you want.
So.. something like this:
material Water/Wake
{
technique
{
pass
{
lighting off
scene_blend alpha_blend
depth_write off

texture_unit
{
texture smoke.png
}
}
technique
{
lighting off
scene_blend alpha_blend
scheme_name HydraxDepth

texture_unit{
texture FullTransparentTexture.png
}
}
}
}
must work!

Remember that if you use your custom Hydrax depth technique you shouldn't call Hydrax::MaterialManager::addDepth...

Post results

Xavi

I think the best way is to use a custom Hydrax depth technique, just add in your particle material a new technique with "HydraxDepth" scheme name and a transparent colour pass, so the particles won't be visible for the Depth RTT, and you'll get the effect you want.
So.. something like this:
material Water/Wake
{
technique
{
pass
{
lighting off
scene_blend alpha_blend
depth_write off

texture_unit
{
texture smoke.png
}
}
technique
{
lighting off
scene_blend alpha_blend
scheme_name HydraxDepth

texture_unit{
texture FullTransparentTexture.png
}
}
}
}
must work!

Remember that if you use your custom Hydrax depth technique you shouldn't call Hydrax::MaterialManager::addDepth...

Post results

Xavi

Hi Xavi,

It works but when the particles are on/in the water, it didn't get rendered at all http://www.youtube.com/watch?v=gyp41AVnXuw I'm trying to obtain this wake effect [attachment=0]med_newwake.jpg[/attachment], possible to achieve it using Particle System? I've been changing my particle script but the result is not good, any advices from anyone?

Thanks,
CG

My fault, the correct way to get it working is using the Hydrax::addDepthTextureTechnique(...), you can find more information here: viewtopic.php?f=20&t=9235
Hope it'll work!

Xavi