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[Tycho Brahe]

or... at least, thats the problem. It still doesnt work... OH WELL

[edit]

tbh, I don't think this is ever going to work.

whatever I do, the difference between the values is MINUSCULE regardless of values fed in, I may give up on this.

[Zaphos]

What value are you using for winZ now?  Not sure what it should actually be; might want to gluProject() a point on your plane (eg 0,0,0) just to see what the winZ should be to be on the plane.

[Ivan]

This is really ugly, since my matrix class is kind of messed up, but hope it helps.

Here's my 2D coordinate test method (tests a 2d coordinate against a polygon).

The matrix passed to it is the full transform matrix of the polygon's object multiplied by the inverse of the current camera matrix.

Code:

bool OpenGLRenderer::test2DCoordinate(float x, float y, Tau::Polygon *poly, const Matrix4 &matrix) {
	GLdouble nearPlane[3],farPlane[3];
	
	GLdouble mv[16];
	Matrix4 camInverse = cameraMatrix.inverse();	
	Matrix4 cmv;
	cmv.identity();
	cmv = cmv * camInverse;
	
	for(int i=0; i < 16; i++) {
		mv[i] = cmv.ml[i];
	}
	
	GLint vp[4];
	glGetIntegerv( GL_VIEWPORT, vp );
	
	gluUnProject(x, yRes - y, 0.0, mv, sceneProjectionMatrix, vp,  &nearPlane[0], &nearPlane[1], &nearPlane[2]);
	gluUnProject(x, yRes - y, 1.0, mv, sceneProjectionMatrix, vp,  &farPlane[0], &farPlane[1], &farPlane[2]);
	
	Vector3 nearVec(nearPlane[0], nearPlane[1], nearPlane[2]);
	Vector3 farVec(farPlane[0], farPlane[1], farPlane[2]);
		
	Vector3 dirVec = farVec - nearVec;	
	dirVec.Normalize();
	
	Vector3 hitPoint;
	
	Matrix4 fullMatrix = matrix;
	
	if(poly->getVertexCount() == 3) {
		return rayTriangleIntersect(Vector3(0,0,0), dirVec, fullMatrix * (*poly->getVertex(0)), fullMatrix  * (*poly->getVertex(1)), fullMatrix *  (*poly->getVertex(2)), &hitPoint);
	} else if(poly->getVertexCount() == 4) {
		return (rayTriangleIntersect(Vector3(0,0,0), dirVec, fullMatrix * (*poly->getVertex(2)), fullMatrix  * (*poly->getVertex(1)), fullMatrix *  (*poly->getVertex(0)), &hitPoint) ||
				rayTriangleIntersect(Vector3(0,0,0), dirVec, fullMatrix * (*poly->getVertex(0)), fullMatrix  * (*poly->getVertex(3)), fullMatrix *  (*poly->getVertex(2)), &hitPoint));
	} else {
		return false;
	}
}

Here's the ray triangle intersect method for good measure:

Code:

bool Renderer::rayTriangleIntersect(Vector3 ray_origin, Vector3 ray_direction, Vector3 vert0, Vector3 vert1, Vector3 vert2, Vector3 *hitPoint)
{
	float t,u,v;
	t = 0; u = 0; v = 0;
	
	Vector3 edge1 = vert1 - vert0;
	Vector3 edge2 = vert2 - vert0;
	
	Vector3 tvec, pvec, qvec;
	float det, inv_det;
	
	
	pvec = ray_direction.crossProduct(edge2);
	det = edge1.dot(pvec);
	
	if (det > -0.00001f)
		return false;
	
	inv_det = 1.0f / det;
	
	tvec = ray_origin - vert0;
	
	u = tvec.dot(pvec) * inv_det;
	if (u < -0.001f || u > 1.001f)
		return false;
	
	qvec = tvec.crossProduct(edge1);
	
	v = ray_direction.dot(qvec) * inv_det;
	if (v < -0.001f || u + v > 1.001f)
		return false;
	
	t = edge2.dot(qvec) * inv_det;
	
	if (t <= 0)
		return false;
	
	hitPoint->x = ray_origin.x+t*ray_direction.x;
	hitPoint->y = ray_origin.y+t*ray_direction.y;
	hitPoint->z = ray_origin.z+t*ray_direction.z;	
	
	return true;	
}

[Tycho Brahe]

@Zaphos

you, sir, are a god.

you've managed to solve all my problems, and in less than a day.

Thanks!

I used your idea of using gluProject() to get the correct z value, then fed that into gluUnProject() to get the right coordinates.

Again, Many thanks.

[Zaphos]

Haha, no worries -- glad it works

[Tycho Brahe]

Just realised that, looking back over the thread that anyone else looking for the answer may not be able to get it, so here is the code I finally settled on for anyone else with the same problem.

so here it is:

Code:

b2Vec2 CALCULATEPOS(int x, int y)
{
	
    
    int viewport[4];
    double modelview[16], projection[16];

    glGetIntegerv(GL_VIEWPORT, viewport);
    glGetDoublev(GL_MODELVIEW_MATRIX, modelview);
    glGetDoublev(GL_PROJECTION_MATRIX, projection);

    int mx = x;
    int my = viewport[3]-y;

    GLdouble WinX,WinY,WinZ;
	
    gluProject(0,0,0,modelview, projection, viewport, &WinX,&WinY,&WinZ);

    GLdouble X,Y,Z;
    gluUnProject((double)mx, (double)my,WinZ, modelview, projection, viewport, &X, &Y, &Z);
    //printf("x:%f   y:%f   z:%f\n",(float)WinX,(float)WinY,(float)WinZ);
	
    float Xf,Yf,Zf;
	
    Xf = (float)X;
	
    Yf = (float)Y;
	
    Zf = (float)Z;
	
    //printf("X:%f, Y:%f, Z:%f\n",Xf,Yf,Zf);

	
    b2Vec2 Return(Xf,Yf);
	
    return Return;

}

(btw this uses some data types from box2d (like b2vec2);