calculating the frustum

glTranslatef( l->center[0], l->center[1], l->center[2] );                                glGetFloatv( GL_MODELVIEW_MATRIX, modelView_shadow );                                DrawScene();                                glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, 0 );                                glDisable( GL_POLYGON_OFFSET_FILL );                        glPopAttrib();                glPopMatrix();        glMatrixMode( GL_PROJECTION );        //here we get the matrix needed later to draw the shadows correctly        glMultMatrixf( modelView_shadow );        glGetFloatv( GL_PROJECTION_MATRIX, l->shadow_pmv );

         //for( int i = 0; i < NUMLIGHTS; i++ ){        //      if( !light.isEnabled )         //              break; //no need to do anything        Light* l = light;        //set set and pop the matrixes so nothing is saved        //NOTE: NOT OGL3.0, needs to be changed, how I dont know        glMatrixMode( GL_PROJECTION );        glPushMatrix();                glMatrixMode( GL_MODELVIEW );                glPushMatrix();                        //set the viewport so we only draw what the map can haddel                        //dont belive this is OGL3.0 either                        //also very similar to sissors test, speed test??                        glPushAttrib( GL_VIEWPORT_BIT );                        glViewport( 0, 0, l->width, l->height );                                //prevent z-fighting                                glPolygonOffset( 1.0, 4096.0 );                                glEnable( GL_POLYGON_OFFSET_FILL );                                glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, shadow1FBO );                                glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );                                glTranslatef( l->center[0], l->center[1], l->center[2] );                                glGetFloatv( GL_MODELVIEW_MATRIX, tmp );                                Inverse( mvInv, tmp );                                DrawScene();                                glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, 0 );                                glDisable( GL_POLYGON_OFFSET_FILL );                        glPopAttrib();                glPopMatrix();        glMatrixMode( GL_PROJECTION );                glGetFloatv( GL_PROJECTION_MATRIX, tmp );                Inverse( projInv, tmp );        glPopMatrix();        glMatrixMode( GL_MODELVIEW );

        glPushMatrix();                glMultMatrixf( mvInv );                glMultMatrixf( projInv );                glColor3f( 1.0, 0.0, 0.0 );                DrawUnitCube();        glPopMatrix();

void Inverse(float dst[16], float src[16]){        dst[0] = src[0];        dst[1] = src[4];        dst[2] = src[8];        dst[3] = 0.0f;        dst[4] = src[1];        dst[5] = src[5];        dst[6]  = src[9];        dst[7] = 0.0f;        dst[8] = src[2];        dst[9] = src[6];        dst[10] = src[10];        dst[11] = 0.0f;        dst[12] = -(src[12] * src[0]) - (src[13] * src[1]) - (src[14] * src[2]);        dst[13] = -(src[12] * src[4]) - (src[13] * src[5]) - (src[14] * src[6]);        dst[14] = -(src[12] * src[8]) - (src[13] * src[9]) - (src[14] * src[10]);        dst[15] = 1.0f;}

    friend matrix4 inverse( const matrix4 & m) {        matrix4 minv;        T r1[8], r2[8], r3[8], r4[8];        T *s[4], *tmprow;        s[0] = &r1[0];        s[1] = &r2[0];        s[2] = &r3[0];        s[3] = &r4[0];        register int i,j,p,jj;        for(i=0;i<4;i++) {            for(j=0;j<4;j++) {                s[j] = m.element(i,j);                if(i==j) s[j+4] = 1.0;                else     s[j+4] = 0.0;            }        }        T scp[4];        for(i=0;i<4;i++) {            scp = T(fabs(s[0]));            for(j=1;j<4;j++)                if(T(fabs(s[j])) > scp) scp = T(fabs(s[j]));            if(scp == 0.0) return minv; // singular matrix!        }        int pivot_to;        T scp_max;        for(i=0;i<4;i++) {            // select pivot row            pivot_to = i;            scp_max = T(fabs(s/scp));            // find out which row should be on top            for(p=i+1;p<4;p++)                if (T(fabs(s/scp)) > scp_max) {                    scp_max = T(fabs(s/scp));                    pivot_to = p;                }            // Pivot if necessary            if(pivot_to != i) {                tmprow = s;                s = s[pivot_to];                s[pivot_to] = tmprow;                T tmpscp;                tmpscp = scp;                scp = scp[pivot_to];                scp[pivot_to] = tmpscp;            }            T mji;            // perform gaussian elimination            for(j=i+1;j<4;j++) {                mji = s[j]/s;                s[j] = 0.0;                for(jj=i+1;jj<8;jj++)                    s[j][jj] -= mji*s[jj];            }        }        if(s[3][3] == 0.0) return minv; // singular matrix!  //        // Now we have an upper triangular matrix.        //        //  x x x x | y y y y        //  0 x x x | y y y y         //  0 0 x x | y y y y        //  0 0 0 x | y y y y        //        //  we'll back substitute to get the inverse        //        //  1 0 0 0 | z z z z        //  0 1 0 0 | z z z z        //  0 0 1 0 | z z z z        //  0 0 0 1 | z z z z         //        T mij;        for(i=3;i>0;i--) {            for(j=i-1;j > -1; j--) {                mij = s[j]/s;                for(jj=j+1;jj<8;jj++)                    s[j][jj] -= mij*s[jj];            }        }        for(i=0;i<4;i++)            for(j=0;j<4;j++)                minv(i,j) = s[j+4] / s;        return minv;    }