hi all! this is my code: -------------------------------------------------------------------------------- #include <stdio.h> #include <stdlib.h> #include <gl\glut.h> #include <ode\ode.h> dWorldID aWorld; dSpaceID aSpace; float cycle = 0, fade; dJointGroupID aContactGroup; dBodyID bodies; dGeomID geoms; GLfloat colors[4]; dGeomID baseGeoms; unsigned int contactsThisFrame; void kglTransformByODEGeom(dGeomID geom) { const dReal *p = dGeomGetPosition(geom); const dReal *R = dGeomGetRotation(geom); GLdouble glm[16]; glm[0] = R[0]; glm[1] = R[4]; glm[2] = R[8]; glm[3] = 0; glm[4] = R[1]; glm[5] = R[5]; glm[6] = R[9]; glm[7] = 0; glm[8] = R[2]; glm[9] = R[6]; glm[10] = R[10];glm[11] = 0; glm[12] = p[0]; glm[13] = p[1]; glm[14] = p[2]; glm[15] = 1; glMultMatrixd(glm); } static void odeNearCallback(void *data, dGeomID g1, dGeomID g2) { dBodyID b1 = dGeomGetBody(g1), b2 = dGeomGetBody(g2); if (b1 && b2 && dAreConnected(b1, b2)) return; dContact contact; dCollide(g1, g2, 1, &contact.geom, sizeof(dContact)); contact.surface.mode = 0; contact.surface.mu = 20.0; dJointAttach(dJointCreateContact(aWorld, aContactGroup, &contact), b1, b2); contactsThisFrame++; } void myGlutResize(int w, int h) { glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.0, (GLfloat)w / h, 1.0, 120.0); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslatef(0, -6, -20); } void myGlutIdle(void) { const float step = 1.0/120; cycle = fmod(cycle + step / 4, 1); fade = fabs(cycle * 2 - 1); contactsThisFrame = 0; dSpaceCollide(aSpace, NULL, &odeNearCallback); dWorldStep(aWorld, step); dJointGroupEmpty(aContactGroup); const dReal *cvel = dBodyGetLinearVel(bodies); dBodyAddForce(bodies, -cvel[0] * 0.5, -cvel[1] * 0.5, -cvel[2] * 0.5); glutPostRedisplay(); } void myGlutDisplay(void) { glClearColor(fade * 0.15, 0, 0, 1); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glPushMatrix(); kglTransformByODEGeom(geoms); glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, colors); glColor3f(fade * 1.5, 0, 0); glRotatef(90, 1, 0, 0); glutSolidSphere(0.5, 29, 29); glEnable(GL_LIGHTING); glPopMatrix(); glutSwapBuffers(); } void specialkey (int key, int x, int y) { switch (key) { case GLUT_KEY_UP: // improve here glutPostRedisplay(); break; case GLUT_KEY_DOWN: // improve here glutPostRedisplay(); break; case GLUT_KEY_LEFT: // improve here glutPostRedisplay(); break; case GLUT_KEY_RIGHT: // improve here glutPostRedisplay(); break; } } int main(int argc, char **argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); glutInitWindowSize(400, 300); glutInitWindowPosition(100, 100); glutCreateWindow("Test"); glutDisplayFunc(myGlutDisplay); glutReshapeFunc(myGlutResize); glutIdleFunc(myGlutIdle); glutSpecialFunc (specialkey); glPolygonOffset(1, 1); glDepthFunc(GL_LEQUAL); glEnable(GL_POLYGON_OFFSET_FILL); glEnable(GL_DEPTH_TEST); glEnable(GL_CULL_FACE); glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); myGlutResize(400, 300); dInitODE(); aWorld = dWorldCreate(); aSpace = dHashSpaceCreate(aSpace); aContactGroup = dJointGroupCreate(0); baseGeoms = dCreatePlane(aSpace, 0, 1, 0, 0); dWorldSetGravity(aWorld, 0, -9.81, 0); dWorldSetERP(aWorld, 0.4); dWorldSetCFM(aWorld, 1e-10); dMass mass; dMassSetBox(&mass, 1.0, 1, 1, 1); bodies = dBodyCreate(aWorld); dBodySetMass(bodies, &mass); geoms = dCreateSphere(aSpace, 0.5); dGeomSetBody(geoms, bodies); dBodySetPosition(bodies, 0, 10, 0); colors[0] = 1; colors[1] = 0; colors[2] = 0; colors[3] = 1; glutMainLoop(); return 0; } -------------------------------------------------------------------------------- It's a simple ball falling down on a plane. Now, I want to improve the program adding a simple interaction: if I press an arrow, the plane under the ball should rotate around X and/or Z axis. I tried both setRotation and setParams functions related to baseGeoms, but the ball is thrown away from the plane, out of the viewport!