java - How to calculate a rectangular prism using min/max of X, Y, and Z vertices -


i want make game player on 3d plane, able collide objects around him. plan collisions wrapping 3d models in game invisible rectangles cannot entered. have written code calculate min/max of x,y, , z of each vertex find highest , lowest point of each vertex. how make rectangular prism?

here code far:

public collisionmodel(list<vector3f> vert) {     float xlow = 1000;     float xhigh = 0;     float ylow = 1000;     float yhigh = 0;     float zlow = 1000;     float zhigh = 0;     for(vector3f v : vert) {         if(v.x > xhigh) {             xhigh = v.x;         } else if(v.x < xlow) {             xlow = v.x;         }         if(v.y > yhigh) {             yhigh = v.y;         } else if(v.y < ylow) {             ylow = v.y;         }         if(v.z > zhigh) {             zhigh = v.z;         } else if(v.z < zlow) {             zlow = v.z;         }     } }

  1. the initial value of min,max should first vertex not hard-coded 0,1000 !!!
  2. you find min,max gives bounding box called prism.

now need collision testing. problem object can move/rotate ... need apply transformations box first. let construct bounding box vertexes first. in 3d 8 points:

p0 = ( xlow  , ylow , zlow  ) p1 = ( xhigh , ylow , zlow  ) p2 = ( xhigh , yhigh, zlow  ) p3 = ( xlow  , yhigh, zlow  ) p4 = ( xlow  , ylow , zhigh ) p5 = ( xhigh , ylow , zhigh ) p6 = ( xhigh , yhigh, zhigh ) p7 = ( xlow  , yhigh, zhigh )

now apply object transformations each of them. , lastly need add collision test. want test if 2 bounding boxes collide or not. need test if edge line of bbox1(q0..q7) intersects face bbox2(p0..p7). faces are:

p0,p1,p2,p3 p4,p5,p6,p7 p0,p1,p5,p4 p1,p2,p6,p5 p2,p3,p7,p6 p3,p0,p4,p7

and edge lines are:

q0,q1 q1,q2 q2,q3 q3,q0 q4,q5 q5,q6 q6,q7 q7,q4 q0,q4 q1,q5 q2,q6 q3,q7

for intersection need google equation (i lazy derive or search you) here first google hit found:

yes can use triangle vs. line intersection face 2 joined triangles ... there option , convert lines coordinate system of other bbox , compute points each line 1 of x,y,z = min , max , test if other 2 coordinates in range or not ..


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