need some help with generating geometry matrix


    Jun 13 2012 | 11:44 pm
    hi! i am trying to create simple cube by sending geometry matrix to jit.gl.mesh. i have read a lot about geometry matrices, verticles and stuff like that but still cant find the clue. i rid that when drawing objects using draw_mode tri_grid the verticles are connected either to neighbor from the same plane and the other plane. i thought that i will create rectangle of verticles with constant z value 1 in the first dim, and then just copy values, changing z to -1 into the second dimmension. the result is something like unfinished, open cube. so my questions are:
    -why would we even need 2 dimmension matrices for geometry? -why the smallest dimmensions to draw the cube correctly is "dim 8 8"? isnt 64 points for creating simple shape quite lot? -in my patch under "matrix data from jit.gl.gridshape" comment there are jit.cellblock. why a lot of values are repeated? - what for there are two verticles in the middle of two sides?
    thanks for advice! adam
    `

    • Jun 14 2012 | 9:30 pm
      up up >)
    • Jun 15 2012 | 11:14 am
      Hi, I can't really help you but maybe this image can do.
    • Jun 17 2012 | 11:25 pm
      thanks, thats really helpfull. however i have got no idea how to understand the format of the matrix esspecially when it comes to draw_mode: quad_grid and tri_grid and multidimmensional arrays...
      jitter "appendix b: the opengl matrix format" says that
      "quad_grid: If the geometry matrix has two dimensions, quadrilaterals are drawn which link each vertex to its neighbors in the matrix to form a surface. "
      but it has nothing to do with matrixoutput of gridshape - that couldnt be for example 16 X 2 dim... is there any tutorial, or helpfile that i am missing, dealing with geometry matrices?