converting from ortho to perspective view

[bytebucket]

that's correct. it was a typo when I posted the code I'm calling glLoadIdentity first, then glTranslate.

[Durga Prasad]

I have the set the ortho for my data with these boundaries and can view view it.I followed the steps to convert ortho to perspective suggested in this thread and I get blank screen.Can you suggest the soultion..

Xmin=398291.437500
Xmax=400033.000000
Ymin=135049.078125
Ymx=137133.796875
Zmin=-5.624723
Zmax=84.187180

Ortho
=====

void resizeGL(int w, int h)
{
if(h<=0) h=1 ;

//To Preserve Aspect Ratio
float fWorldW=sBoundingBox.fMaxX-sBoundingBox.fMinX;
float fWorldH=sBoundingBox.fMaxY-sBoundingBox.fMinY;
float fWorldR=fWorldW/fWorldH;
float fViewportR=w/h;
if(fWorldR>fViewportR)
{
glViewport(10,50,w,w/fWorldR);
}
else
{
glViewport(10,50,h*fWorldR,h);
}

glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
//Assign Bounding Box Coordinates of Shapefile to glOrtho()
glOrtho(sBoundingBox.fMinX, sBoundingBox.fMaxX,sBoundingBox.fMinY,sBoundingBox .fMaxY,sBoundingBox.fMinZ,sBoundingBox.fMaxZ);

printf("xmin= %f,xmax=%f,ymin= %f,ymax=%f,zmin= %f,zmax=%f",sBoundingBox.fMinX, sBoundingBox.fMaxX,sBoundingBox.fMinY,sBoundingBox .fMaxY,sBoundingBox.fMinZ,sBoundingBox.fMaxZ);
glMatrixMode(GL_MODELVIEW);
}


void GLDraw()
{
glClear (GL_COLOR_BUFFER_BIT);
glLoadIdentity ();
glColor4f(1.0,0.0,0.0,1.0);
float xdelta=(sBoundingBox.fMinX+sBoundingBox.fMaxX)/2;
float ydelta=(sBoundingBox.fMinY+sBoundingBox.fMaxY)/2;
float zdelta=(sBoundingBox.fMinZ+sBoundingBox.fMaxZ)/2;

glPushMatrix();
glTranslatef(xdelta,ydelta,zdelta);
glRotatef(-45.0f,1,0,0);
glTranslatef(-xdelta,-ydelta,-zdelta);
DrawPolygonShapefile1();//Rendering logic
glPopMatrix();
glFlush();
}

Perspective
==========

double ConvertDegsToRads (double d)
{
return d * M_PI/180.0;
}

void resizeGL(int w, int h)
{
if(h<=0) h=1 ;
//glViewport (0, 0, (GLsizei) w, (GLsizei) h);

//To Preserve Aspect Ratio
float fWorldW=sBoundingBox.fMaxX-sBoundingBox.fMinX;
float fWorldH=sBoundingBox.fMaxY-sBoundingBox.fMinY;
float fWorldR=fWorldW/fWorldH;
float fViewportR=w/h;
if(fWorldR>fViewportR)
{
glViewport(10,50,w,w/fWorldR);
}
else
{
glViewport(10,50,h*fWorldR,h);
}

glMatrixMode(GL_PROJECTION);
glLoadIdentity();

GLdouble vvLeft = sBoundingBox.fMinX;
GLdouble vvRight = sBoundingBox.fMaxX;
GLdouble vvBottom =sBoundingBox.fMinY;
GLdouble vvTop = sBoundingBox.fMaxY;
GLdouble vvNear = sBoundingBox.fMinZ;
GLdouble vvFar = sBoundingBox.fMaxZ;

GLdouble vvDepth = vvFar - vvNear;
GLdouble vvHeight = vvTop - vvBottom;

const GLdouble vvFovDegs = 45.0;
GLdouble vvFovRads = ConvertDegsToRads(vvFovDegs);

vvNear = (vvHeight / 2.0) / tan(vvFovRads / 2.0);
vvFar = vvNear + vvDepth;

glFrustum(vvLeft, vvRight, vvBottom, vvTop, vvNear, vvFar);

glMatrixMode(GL_MODELVIEW);

glTranslated(0,0,-(vvNear + (vvDepth / 2.0)));

glLoadIdentity();

}

void GLDraw()
{

glClear (GL_COLOR_BUFFER_BIT);
glLoadIdentity ();
DrawPolygonShapefile1();
glFlush();
}