from pandac.PandaModules import *  
import direct.directbase.DirectStart
from direct.showbase.DirectObject import DirectObject

class LoaderMap(DirectObject):
     def __init__(self):
         self.node = GeomNode('gnode')
         self.gvd = GeomVertexData('name', GeomVertexFormat.getV3t2(), Geom.UHStatic)     
         self.geom = Geom(self.gvd)
         self.prim = GeomTriangles(Geom.UHStatic)
         self.vertex = GeomVertexWriter(self.gvd, 'vertex')
         self.texcoord = GeomVertexWriter(self.gvd, 'texcoord')
         self.tex = loader.loadTexture('1.png')
         self.x = 0
         self.y = 0
         self.accept('x',self.x1)
         self.accept('y',self.y1)
         self.accept('g',self.add_vert)
         self.Vert0 = 0
         self.Vert1 = 1
         self.Vert2 = 2
         self.Vert3 = 3
         self.nomer_GeomState = 0
     def x1(self):
         self.x +=1
     def y1(self):
         self.y +=1
     def add_vert(self):
         self.vertex.addData3f(self.x-0.5, self.y+0.5, 0)
         self.texcoord.addData2f(1, 1)  
         self.vertex.addData3f(self.x-0.5, self.y-0.5, 0)
         self.texcoord.addData2f(1, 0)
         self.vertex.addData3f(self.x+0.5, self.y+0.5, 0)
         self.texcoord.addData2f(0, 1)
         self.vertex.addData3f(self.x+0.5, self.y-0.5, 0)
         self.texcoord.addData2f(0, 0)
         self.prim.addVertices(self.Vert0, self.Vert1, self.Vert2, self.Vert3)
         self.prim.addVertices(self.Vert2, self.Vert1)
         self.geom.addPrimitive(self.prim)
         self.node.addGeom(self.geom)
         self.node.setGeomState(self.nomer_GeomState,  
                    self.node.getGeomState(self.nomer_GeomState).addAttrib(TextureAttrib.make(self.tex)))
         self.nomer_GeomState +=1
         self.prim.closePrimitive()
         terrain = render.attachNewNode(self.node)
         terrain.analyze()
         self.vert()
     def vert(self):
         self.Vert0 += 4
         self.Vert1 += 4
         self.Vert2 += 4
         self.Vert3 += 4
          
LoaderMap()
run()

     terrain.bake()
   File "terrain_poligons_right.py", line 64, in bake
     self.geoms[i]['geom'].addPrimitive(self.geoms[i]['prim'])
AssertionError: primitive->check_valid(cdata->_data.get_read_pointer()) at line
370 of c:\buildslave\release_sdk_win32\build\panda3d\panda\src\gobj\geom.cxx