3D terrain picking

Graphics and GPU Programming Programming

Started by polyfrag September 14, 2012 08:22 AM

0 comments, last by MARS_999 11 years, 7 months ago

polyfrag

2,504

Author

September 14, 2012 08:22 AM

Does anybody know how to do 3D terrain picking?

I tried this example but it doesn't work:



CVector3 GetMouse3DCoords()

{

static POINT IMousePos;

//GetCursorPos(&IMousePos);

IMousePos.x = g_mousex;

IMousePos.y = g_mousey;

int IViewPort[4];

glGetIntegerv(GL_VIEWPORT, IViewPort);

unsigned int IDepth;

// Get the Z coordinate for the pixel location

glReadPixels( IMousePos.x, (IViewPort[3] - IMousePos.y ), 1, 1, GL_DEPTH_COMPONENT, GL_UNSIGNED_INT, &IDepth);

int zdepth;

float IDistTermInv;

glGetIntegerv(GL_DEPTH_BITS, &zdepth);

switch(zdepth)

{

case 16:

  IDistTermInv = (float) 1.5259018967e-5; //65535

  break;

default:

  IDistTermInv = (float) 2.32830643708e-10; // 4294967295

  break;

}

double IDistance = (float) IDepth * IDistTermInv;



double IModelMatrix[16], IProjMatrix[16];

glGetDoublev(GL_MODELVIEW_MATRIX, IModelMatrix);

glGetDoublev(GL_PROJECTION_MATRIX, IProjMatrix);

double IPos[3];

gluUnProject(IMousePos.x, (IViewPort[3] - IMousePos.y), IDistance, IModelMatrix, IProjMatrix, IViewPort, &IPos[0], &IPos[1], &IPos[2]);

CVector3 ITarget = CVector3( IPos[0], IPos[1], IPos[2] );



return ITarget;

}

MARS_999

1,627

September 18, 2012 03:49 AM

I use CML get it here....

http://cmldev.net/



static inline cml::vector3d GetScreenPosition(cml::vector3f& point)

   {

	  cml::matrix44d_c projection, modelview, viewport;

	  GLint vp[4];

	  double* proj = projection.data();

	  double* mv   = modelview.data();

	  glGetDoublev(GL_PROJECTION_MATRIX, proj);

	  glGetDoublev(GL_MODELVIEW_MATRIX, mv);

	  glGetIntegerv(GL_VIEWPORT, vp);

	  point[1] = float(vp[3]) - point[1];

	  glReadPixels(int(point[0]), int(point[1]), 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &point[2]);

	  cml::matrix_viewport(viewport, double(vp[0]),

							  double(vp[2]),

							  double(vp[1]),

							  double(vp[3]),

							  cml::z_clip_neg_one,

							  0.0, 1.0);

	  return cml::unproject_point(modelview, projection, viewport, point);

   }

3D terrain picking

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