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Member Since 19 Jan 2012
Offline Last Active Feb 10 2014 03:21 PM

Topics I've Started

google sketchup model as fbx using meshparts instead of only mesh

05 February 2014 - 12:58 PM

Hi all,


So I have made the outmost simple tree model in google sketchup pro, and when I export it to fbx and import it in xna, the model comes out as 2 meshes, each with 1 mesh part, here is the picture of the structure and the object:


Attached File  sketchupModel.png   71.43KB   7 downloadsAttached File  sketchupModel_full.png   116.24KB   7 downloads


I have tried grouping, and making a component, but its always the same result. I don't want to merge the 2 objects since it will remove the part of the trunk that's inside the leafs (already tried that) which in result will add way more quads than the original object (the new quads will be added in the join point of the trunk and the base of the leafs pyramidal object), and I don't want that.


Any ideas how to make the magic? 


The result should be



-ModelMeshpart0 (here goes the trunk)

-ModelMeshpart1 (here goes the leafs... or the other way around, but both as modelmeshparts, and not modelmeshs each)


Thanks in advance.

fbx tree with billboard leafs, but leaf quads are already made

01 February 2014 - 11:35 AM

Hi all,


I imported an fbx tree model into an editor I'm doing, and saw that the tree already came with the leafs as quads (tons of quads actually), and I would like those to work as billboards, and all the leaf quads come in a single modelmeshpart section. 


To be honest looking at the tree image I think they are way too many quads and its actually a waste of quad to put them all as billboards, but for learning purposes I would like to make them work as billboards. Is there a way to make already made quads work as billboards?


thanks in advance for all the help.


Here is an image of the tree with and without alpha blending.


Attached File  alpha.png   310.72KB   7 downloads


Attached File  no alpha.png   261.43KB   5 downloads

GeoClipmap in GPU tutorial for XNA 4.0, anyone knows of one?

16 August 2013 - 07:38 PM

Hi all, 


Title says it all, but I'm trying to learn how to implement geoClipmaps in xna, I have found the gpu gems 2 papers and all that, but honestly, I seem to be too dumb to apply it, I need for dummies, step by step tutorial of how to do it.


Can anyone please help me.... *putting kitty face*





spherical and cylindrical billboarding

14 August 2013 - 11:51 PM

Hi all, 


I seem to get the theory behind this, first put 4 points at the same spot, map some coord, have the HLSL stretch those coord so that we make a quad, put texture in the middle.


For cylindrical:


Then on HLSL we calculate the position of the point, by taking the position and multiplying it by the world matrix only.. ? not sure here.


Then we create the lookat vector by taking the position - camera position.


We have our up vector which is like (0,1,0)


And I think we do a cross between the lookat vector and the up vector, so that we find the normal to both vector... this seems to be like a side looking kind of vector, and Normalize that side vector.


we then stretch the 4 points, into the final position.

-by adding a fix amount to the x cord and multiplying it by the side vector

-by adding a fix amount to the y cord and multiplying it by the up vector.


get view/projection matrix, and multiply the final position by the view projection matrix.


Finish it up by sending it the pixel shader and applying the texture.


Now, how do I do the same thing for the spherical billboard?





tree level of detail according to distance

12 August 2013 - 09:47 PM

Hi all, 


I have a 3D terrain (around 16km*16m), and I'm laying out trees... but my trees are 3D, take a lots of vertices, and I cannot put that much such as in putting in a forest.


Now I could put crossed image trees (2 quads in a cross shape), for my medium distance trees, and a single billboard quad for the further away trees... but, the question is how to I make the program switch between my 3d trees, 2 quad trees and 1 billboard tree base on the distance to camera?