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Sword7

Member Since 22 Apr 2013
Offline Last Active Apr 28 2016 07:32 PM

Topics I've Started

Terrain LOD - split decision using fov

17 April 2016 - 09:59 AM

Folks,

I am figuring formula for split decision by using varying FOV. I read some books about terrain 3D engine and some papers but they did not mention any formula for split decision. One of books mentioned simple formula by using metric errors and system errors but did not mention more information about error determination.

Does anyone know any source about clearly explanation about formula for split decision by using metric errors and varying FOV?

I am trying to develop procedural planet routines for orbiter simulation.

Thanks!

Help! iterator problem

30 December 2013 - 08:50 PM

Folks,

 

I am working on my orbital flight simulator in C++ language.  I tried to implement find function call in class StarDatabase but encountered two blocking error messages. With using 'iterator', compiler complained about 'no match for operator ='.  I changed to 'const_iterator' and it worked but complaint 'invalid conversion from const to non const' at return statement.  That's why I want to return non const Star class to the caller to update it.  Does anyone know any solution or working around.

 

Look at my code below.

 

Thanks,

Sword7

std::vector<Star> unsortedStars;
Star *StarDatabase::find(uint32 catalogNumber) const
{
	std::vector<Star>::iterator iter;
	for (iter = unsortedStars.begin(); iter != unsortedStars.end(); iter++) {
		if ((*iter).getCatalogNumber() == catalogNumber)
			return &(*iter);
	}
	return NULL;
}


Quadcube spherical mapping

18 August 2013 - 08:25 PM

Folks,

 

I am getting fimilar with my OpenGL programming since last Spring and successfully wrote a program to display planet Earth by using ECP spherical mapping (slices and rings division).  Only problem is too tight grids near poles.

 

Now I researched about quadcube spherical programming for cubmap images through Internet.  I found some pages but it do not have sample code about that quadecube grids. Without sample code, I did still not know how to implement code to display quadcube sphere through simple vertexes, indices, and texcoords for glDrawElements function call.

 

Does anyone have any sample/example codes for quadcube sphere mapping for cubemaps?

 

Thanks!

 


Sphere texture mapping - distortion strip problem

23 April 2013 - 08:39 PM

Hello folks,

 

I am writing a small program to display planet earth by using glDrawElements and vertex/indices array.

 

It normally displays planet earth but seam strip between alaska and russia land.  I think that it is a problem with texcoords or glDrawElements function call.  I tried different ways but it always display distrotion strip.  Does anyone know any working around to get rid of distrotion strip?

Look at my code below.

 

Thanks!

Sword7

 

    int    thetaExtent = extent;

    int    phiExtent   = extent/2;

    int    theta1      = theta0 + thetaExtent;

    int    phi1        = phi0 + phiExtent;

    double phiStep     = (PI) / phiExtent;

    double thetaStep   = (2 * PI) / thetaExtent;

 
    double *v = vertices;

    double *t = texCoords;
    for (int phi = phi0; phi <= phi1; phi += ri.step) {

        for (int theta = theta0; theta < theta1; theta += ri.step) {

            *v++ = sin(phi * phiStep) * cos(theta * thetaStep);

            *v++ = cos(phi * phiStep);

            *v++ = sin(phi * phiStep) * sin(theta * thetaStep);



            *t++ = 1 - (theta * (1.0 / thetaExtent));

            *t++ = phi * (1.0 / phiExtent);

        }

    }



    uint16 *i = indices;

    for (int p = 0; p < phiExtent; p++) {

        for (int t = 0; t < thetaExtent; t++) {

            *i++ = p * thetaExtent + t;

            *i++ = p * thetaExtent + (t+1);

            *i++ = (p+1) * thetaExtent + (t+1);

            *i++ = (p+1) * thetaExtent + t;

        }

    }

 
    glVertexPointer(3, GL_DOUBLE, 0, vertices);

    glNormalPointer(GL_DOUBLE, 0, vertices);

    glTexCoordPointer(2, GL_DOUBLE, 0, texCoords);



    glDrawElements(GL_QUADS, nIndices, GL_UNSIGNED_SHORT, indices);

Angular Velocity and Quaternion - problems

23 April 2013 - 08:12 PM

Hello folks,

 

I am new to this gamedev.net forum that I searched for and found.  I searched for angular velocity and quaternion on Google but they did not help so much.  I implemented quaternion and angular velocity control (by using keyboard).  When I pitch to 90 degrees down, I tried to yaw right but it rolls right instead.  At zero Z-axis angle, it normally yaw right or left.  I want to rotate at current local axes, not origin axes.   My code implementation is:

 

dr = (angularVelocity * 0.5) * orientation;

orientation += (dr * dt);

orientation.normalize();

 

Where dt = delta time, dr = delta rotation

 

Does anyone have different angular velocity/quaternion formula to yaw, pitch, and roll at current local axes?

 

Thanks,

Sword7


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