Ligth mooving with camera

OpenGL OpenGL: Basic Coding
1

Hi! Im trying to add lighting to my program, the ligths seams to work as I expect when I load a object, but, when I rotate the camera around it the ligth apear to move with the camera.
Here is a example, the ligth source is located at the point 0,100,0, so the top face of the cube is iluminated (the cube is at point 0,0,0), as I expect.
[ATTACH=CONFIG]1419[/ATTACH]

The problem comes when i move the camera to the bottom of the cube, It lights up as if the ligth source has move with the camera.

[ATTACH=CONFIG]1420[/ATTACH]

I suspect that the problem comes from the Nomal vectors. I calculate the normal vector for the objet (for every surface and vertex) when I load it. Must I update this vectors when I modify the camera?

This is the function that draws the objets



glMatrixMode(GL_MODELVIEW);
glLoadMatrixd(camera->cameraglulookat); //Result from glulookat stored at "camera->cameraglulookat"
glPushMatrix();

glMultMatrixd(aux_obj->trans_matrix); //matrix with the transformations applied to the object
		
        for (f = 0; f < aux_obj->num_faces; f++) {
            glBegin(GL_POLYGON);
 
            for (v = 0; v < aux_obj->face_table[f].num_vertices; v++) {
                v_index = aux_obj->face_table[f].vertex_table[v];
				
				if(tilum==FLAT)
					glNormal3f(aux_obj->face_table[f].normal.x,
                                                        aux_obj->face_table[f].normal.y,
                                                        aux_obj->face_table[f].normal.z);
				else //tilum==SMOOTH
					glNormal3f(aux_obj->vertex_table[v_index].normal.x,
                                                        aux_obj->vertex_table[v_index].normal.y,
                                                        aux_obj->vertex_table[v_index].normal.z);
				
				
			
                glVertex3d(aux_obj->vertex_table[v_index].coord.x,
                               aux_obj->vertex_table[v_index].coord.y,
                               aux_obj->vertex_table[v_index].coord.z);

            }
            glEnd();
        }
glPopMatrix();

Thanks!

UPDATE:

I found the solution, the matrix at GL_MODELVIEW also affect to the ligth source, so, adding a line to set the ligth position again at 0,100,0 before drawing has solved the problem
Here is the updated code:



glMatrixMode(GL_MODELVIEW);
glLoadMatrixd(camera->cameraglulookat); //Result from glulookat stored at "camera->cameraglulookat"
glPushMatrix();

glMultMatrixd(aux_obj->trans_matrix); //matrix with the transformations applied to the object


//--------------------------------------------------------------------------------------------------------------------------------
glLightfv( GL_LIGHT1, GL_POSITION,  listaluces[1].position); // listaluces[1].position = {0,100,0,0};
//-------------------------------------------------------------------------------------------------------------------------------- 
        for (f = 0; f < aux_obj->num_faces; f++) {
            glBegin(GL_POLYGON);
 
            for (v = 0; v < aux_obj->face_table[f].num_vertices; v++) {
                v_index = aux_obj->face_table[f].vertex_table[v];
				
				if(tilum==FLAT)
					glNormal3f(aux_obj->face_table[f].normal.x,
                                                        aux_obj->face_table[f].normal.y,
                                                        aux_obj->face_table[f].normal.z);
				else //tilum==SMOOTH
					glNormal3f(aux_obj->vertex_table[v_index].normal.x,
                                                        aux_obj->vertex_table[v_index].normal.y,
                                                        aux_obj->vertex_table[v_index].normal.z);
				
				
			
                glVertex3d(aux_obj->vertex_table[v_index].coord.x,
                               aux_obj->vertex_table[v_index].coord.y,
                               aux_obj->vertex_table[v_index].coord.z);

            }
            glEnd();
        }
glPopMatrix();
2

Where is your light set up ? The subject is about lighting, but there is no code about lighting.

Here you can read some information about why your light might (or not) move related to your camera.

3

[QUOTE=Silence;1285088]Where is your light set up ? The subject is about lighting, but there is no code about lighting.

Here you can read some information about why your light might (or not) move related to your camera.[/QUOTE]

Thanks! I found the solution to my problem, I updated the post, maybe It would help somebody with the same problem in the future :slight_smile: