Jungle Boy

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  1. Edge vs Edge Collision Detection

    but... but... how the collision detection will work without rotation? just imagine a cube rotating, not translating, i'll never get a collision. I can't figure out how to make the collision detections work without time-slicing in the case of edge-edge. Perphaps generating a volume with vertices of edge1(t0) edge1(t1) and testing it against edge0... i don't know how to proceed :/ or should i wait the delivery of Real-time Collision Detection from amazon? -.-
  2. Edge vs Edge Collision Detection

    Quote:Edge0 is assumed to be static, Vrel being the realtive velocity of edge1 from edge0 (Vrel = V1 - V0). But the velocity varies along the edge, should i use the midpoint's velocity to calculate the vel from an edge?
  3. Edge vs Edge Collision Detection

    Hi leoptimus Sorry my delay. I'm doing my first engine and i chose ray rasting for intersections just because it looks good hehe i don't know about performance between ray rasting and others... Badouel's algorithm for ray-casting: http://graphics.cs.msu.su/courses/cg_el99/intersect.html i'm using it, a very fast way...
  4. Hi folks I have implemented collision detection for the case of vertex vs face (in the tri-tri scene) through the Badouel's algorithm for ray(vertex)-tracing. I do the tracing with final e initial position of the vertices and test against the faces. It gives me not very fast way to find collisions but a very accurate method. In the same way, i'm looking for a method to test edge vs edge. Any help will be appreciated, thx.
  5. Contact Resting - Quadratic Programming

    Thx MrRowl it's exactly what i wanted ;P
  6. Contact Resting - Quadratic Programming

    thx for reply David :) But i'm totally ignorant about that and not very concerned about "how to solve quadratic programming" right now. I googled several times for LCP implemented algorithms but i didn't find :/ Do you know where i can find an implemented of LCP algorithm?
  7. hi guys I'm looking for a fast QP solver for my physic's implementation with friction (for the contact resting, specifically). Is there a "standard algorithm" for that? Thx
  8. AABB Tree - Where's the poly o_O?

    I'm very pleased with your replies, guys ;P noisecrime, your diagrams explain very well this approach to build an AABB Tree and collision checking, i think you must make a tuto for that ;P, its not very easy to find information about AABB Tree, thanks. I'm thinking about the possibility to use a mix of octree and aabbtree. The first one would be to carry polys of static meshes (like the buildings, trees, terrain) and also, in the leaf nodes, to store information about the intersecting AABB of dynamic meshes, the last one without regard of its polys and how many polys a leaf node of an octree should have (of course, in this way, same dynamic meshes would be in more than one octree leaf node). So to do frustum culling, i would use the leaf nodes of octree to render its polys of static meshes normally and dynamic meshes (the last one, entirely) and to do collision checking, for static_mesh vs dynamic_mesh i would use the octree leaf nodes where the dynamic_mesh lies and test its AABBs (of the dynamic mesh) against the polys (of static meshes) of the corresponding leaf nodes. Thus i believe the management of octree will be very easy and fast because i won't have to rebalance its nodes (because the static meshes don't move and the dynamic meshes will be stored without regard of its quantity of polys and so on). Anyone have implemented something like that? I forgot something?
  9. AABB Tree - Where's the poly o_O?

    http://staff.hangarnet.com.br/horta/intersection.png I believe I expressed myself inadequately. As you can see in this image, the intersection occurs in the bottom box. However, the polygon is only classified in the top box. This will cause a collision test failure, because the collision took place in the bottom box.
  10. I've got a paper that describes what an AABB Tree is and how to build one. With that you can exclude impossible collisions quickly, search for possible collisions, and can find the intercepted poly rapidly. The paper tells that the polys should be classified (i.e. what box it's inside, above or below) about the midpoint of its projection onto the axis. But in this way, some search collisions will fail cuz, although the polys could overlap two boxes on the same level, this algorithm to build an AABB Tree will choose only one box in which this poly will lie. [quote="Paper"] We position the partitioning plane along the longest axis, by choosing, the coordinate on the longest axis where the partitioning plane intersects the axis. We then split the set of primitives into a negative and positive subset corresponding to the respective halfspaces of the plane. A primitive is classified as positive if the midpoint of its projection onto the axis is greater than, and negative otherwise. [/quote]
  11. Detecting if a tri is inside an axis-aligned cube

    oh god, this page has some amazing flash to demonstrate how the SAT works, no more paper needed o_O
  12. Detecting if a tri is inside an axis-aligned cube

    very thanks, guys i founded a SAT explanation here -> http://www.harveycartel.org/metanet/tutorials/tutorialA.html#section1 and tested on a paper ;P thx again
  13. Detecting if a tri is inside an axis-aligned cube

    sorry again, it should be "tri intersects or inside an axis-aligned cube" just a poor english issue it's all about octree construction i need to know which tris are intersecting/inside octree's cubes
  14. Detecting if a tri is inside an axis-aligned cube

    sorry for the "axis-oriented", the correct is "axis-aligned" just edited the title....
  15. Detecting if a tri is inside an axis-aligned cube

    Palidine, your algorithm just check if the vertices is inside the cube a poly could overlap a cube with all it's vertices outside the cube Eelco, is "seperating planes algorithm" the fastest way for this case? thx for your replies