Rotate vertex mass
Blitz3D Forums/Blitz3D Programming/Rotate vertex mass
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| How would I rotate a buffer of stored vertices? The situation would probably call for them to be stored in a vertex buffer(array). I imagine it requres I find the center of the vertex mass, then move them with a sin()/cos() algo depending on the distance from the center? Thanks for any help. |
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| I'm not sure I understand fully, but can you not just add the verts to a mesh and then RotateMesh? |
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| Sure I could, but the situation may call for rotation of specific vertices. |
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| well, I know there's a way to find it using pure math, but one way is to position a pivot oriented in the direction amount you want rotated at the center of mass. Then Tformpoint vertexx,vertexy,vertexz,pivot,themesh for each vertex and tformedx,y,z will hold the new position of the verticex. |
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| Thx bot builder, Ill look into that. |
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| Sure I could, but the situation may call for rotation of specific vertices. I think that's what Big10P was suggesting. Only add the vertices you want to rotate to the mesh. I seem to recall he did some testing with "scratch meshes" and found it to be the fastest way of rotating vertices. When I needed to do this, I did it BotBuilder's way but it's not all that fast. |
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| Probably this is useful: original coords in x0,y0 and z0 result in xl3,yl3 and zl3 (everything is float, of course) ; rotate pitch#, yaw# and roll# ;--------------------------------- xl1#=z0*Sin(roll)+x0*Cos(roll) yl1#=y0 zl1#=z0*Cos(roll)-x0*Sin(roll) xl2#=xl1 yl2#=yl1*Cos(yaw)-zl1*Sin(yaw) zl2#=yl1*Sin(yaw)+zl1*Cos(yaw) xl3#=yl2*Sin(pitch)+xl2*Cos(pitch) yl3#=yl2*Cos(pitch)-xl2*Sin(pitch) zl3#=zl2 ;--------------------------------- |
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| Yes, Sybixsus, that is what i meant ;) ...simply read the verts you want rotated into the scratch-pad mesh, do the rotations, then write the new verts back into your mesh-proper. Bot Builders method using TFormPoint will also work but I expect it would become pretty slow if you wanted to rotate hundreds/thousands of verts as you'd have to individually TFormPoint each vert. Either way, I'm sure you'd find doing the rotations in software (using sin/cos) MUCH slower as I assume using a scratch-pad mesh takes advantage of hardware T&L. |
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