Jump to content

  • Log In with Google      Sign In   
  • Create Account

We're offering banner ads on our site from just $5!

1. Details HERE. 2. GDNet+ Subscriptions HERE. 3. Ad upload HERE.


Ray Casting Issues


Old topic!
Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.

  • You cannot reply to this topic
No replies to this topic

#1 Banded   Members   -  Reputation: 100

Like
0Likes
Like

Posted 04 April 2012 - 11:16 AM

Hey guys so I have been having some issues with my game recently regarding ray casting. I have been working on an rts game and now I have been trying to be able to use my mouse inorder to select units and then tell them where to go. So after researching this I cam to this code.
// This function will find 2 points in world space that are on the line into the screen defined by screen-space( ie. window-space ) point (x,y)
   double mvmatrix[16];
   double projmatrix[16];
   int viewport[4];
   double dX, dY, dZ, dClickY; // glUnProject uses doubles, but I'm using floats for these 3D vectors

   glGetIntegerv(GL_VIEWPORT, viewport);
   glGetDoublev (GL_MODELVIEW_MATRIX, mvmatrix);
   glGetDoublev (GL_PROJECTION_MATRIX, projmatrix);
   dClickY = double (stateInfo.windowHeight - y); // OpenGL renders with (0,0) on bottom, mouse reports with (0,0) on top

   gluUnProject ((double) x, dClickY, 0.0, mvmatrix, projmatrix, viewport, &dX, &dY, &dZ);
Vector3f ClickRayP1 = Vector3f ( (float) dX, (float) dY, (float) dZ );
   gluUnProject ((double) x, dClickY, 1.0, mvmatrix, projmatrix, viewport, &dX, &dY, &dZ);
Vector3f ClickRayP2 = Vector3f ( (float) dX, (float) dY, (float) dZ );
std::cout<<"Ray 1 ("<<ClickRayP1.x<<","<<ClickRayP1.y<<","<<ClickRayP1.z<<")"<<std::endl;
std::cout<<"Ray 2 ("<<ClickRayP2.x<<","<<ClickRayP2.y<<","<<ClickRayP2.z<<")"<<std::endl;


So I understand what is going on here but I am having some issues. To start, the matrixes remain the same even after I move the camera around, so the points I get back are the same when I move the camera, and I cant figure out why. Further more, everything in my game is drawn on the XZ plane, with Y = 0, so how do I get the Z value information for this plane from clicking. I dont know if its useful but I will include the display function too cause it shows the matrix stuff.

void DisplayCallbackFunction(void)
{
/*clear the screen*/
glClearColor(0,0,0,0);
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
drawing3D();
/*draw the game*/
theGame.draw();
GLuint texture;
//draw in 2d
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glOrtho(0.0, WINDOW_SCREEN_WIDTH,0.0, WINDOW_SCREEN_HEIGHT, -1.0, 10.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glDisable(GL_CULL_FACE);
glClear(GL_DEPTH_BUFFER_BIT);
theGame.currentHUD->draw();
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);

/*display buffer*/
glutSwapBuffers();
}

any help will be greatly appreciated as this project is approaching its due date.

Sponsor:



Old topic!
Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.



PARTNERS