OpenGL evaluator only partially lit - c++

Question

I was trying to make a small wave generator in OpenGL with C++, using an evaluator.
However, I haven't had much luck since my evaluator only gets partially lit.
Why does this happen?
Below I include full source code for completeness' sake, you'll probably only have to look at init(), display() and the constants at the top of the file.
#include <gl/glui.h>
#include <math.h>
const int DIMX = 500;
const int DIMY = 500;
const int INITIALPOS_X = 200;
const int INITIALPOS_Y = 200;
// Aspect ratio (calculated on the fly)
float xy_aspect;
// UI aux. matrices
float view_rotate[16] = { 1,0,0,0,
0,1,0,0,
0,0,1,0,
0,0,0,1 };
float obj_pos[] = { 0.0, 0.0, 0.0 };
float obj_pan[] = { 0.0, 0.0, 0.0 };
// Referential axis
double axis_radius_begin = 0.2;
double axis_radius_end = 0.0;
double axis_lenght = 16.0;
int axis_nslices = 8;
int axis_nstacks = 1;
// Light 0 properties
float light0_position[] = {5.0, 5.0, 5.0, 0.0};
float light0_ambient[] = {0.0, 0.0, 0.0, 1.0};
float light0_diffuse[] = {0.6, 0.6, 0.6, 1.0};
float light0_specular[] = {1.0, 1.0, 1.0, 1.0};
float light0_kc = 0.0;
float light0_kl = 1.0;
float light0_kq = 0.0;
double light0x = 5.0;
double light0y = 5.0;
double light0z = 5.0;
double symb_light0_radius = 0.2;
int symb_light0_slices = 8;
int symb_light0_stacks =8;
// Ambient light source properties
float light_ambient[] = {0.5, 0.5, 0.5, 1.0}; /* Set the background ambient lighting. */
// Windowing related variables
int main_window;
GLUquadric* glQ;
GLUI *glui;
const unsigned int gridSize = 40;
float grid[gridSize][gridSize][3];
const int uSize = gridSize;
const int vSize = gridSize;
GLfloat ambient[] = {0.2, 0.2, 0.2, 1.0};
GLfloat position[] = {0.0, 0.0, 2.0, 1.0};
GLfloat mat_diffuse[] = {0.6, 0.6, 0.6, 1.0};
GLfloat mat_specular[] = {1.0, 1.0, 1.0, 1.0};
float mat_shininess[] = {50.0};
void display(void) {
static float value = 0;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
glFrustum( -xy_aspect*.04, xy_aspect*.04, -.04, .04, .1, 50.0 );
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
glTranslatef( obj_pos[0], obj_pos[1], -obj_pos[2]-25 );
glTranslatef( obj_pan[0], obj_pan[1], obj_pan[2] );
glRotated( 20.0, 1.0,0.0,0.0 );
glRotated(-45.0, 0.0,1.0,0.0 );
glMultMatrixf( view_rotate );
glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE);
glEnable(GL_COLOR_MATERIAL);
glColor3f(1.0,0.0,0.0);
glPushMatrix();
glRotated(90.0, 0.0,1.0,0.0 );
gluCylinder(glQ, axis_radius_begin, axis_radius_end,
axis_lenght, axis_nslices, axis_nstacks);
glPopMatrix();
glColor3f(0.0,1.0,0.0);
glPushMatrix();
glRotated(-90.0, 1.0,0.0,0.0 );
gluCylinder(glQ, axis_radius_begin, axis_radius_end,
axis_lenght, axis_nslices, axis_nstacks);
glPopMatrix();
glColor3f(0.0,0.0,1.0);
glPushMatrix();
gluCylinder(glQ, axis_radius_begin, axis_radius_end,
axis_lenght, axis_nslices, axis_nstacks);
glPopMatrix();
light0_position[0] = light0x;
light0_position[1] = light0y;
light0_position[2] = light0z;
glLightfv(GL_LIGHT0, GL_POSITION, light0_position);
glColor3f(1.0,1.0,0.0);
gluQuadricOrientation( glQ, GLU_INSIDE);
glPushMatrix();
glTranslated(light0x,light0y,light0z);
gluSphere(glQ, symb_light0_radius, symb_light0_slices, symb_light0_stacks);
glPopMatrix();
gluQuadricOrientation( glQ, GLU_OUTSIDE);
gluQuadricDrawStyle(glQ, GLU_FILL);
gluQuadricNormals(glQ, GLU_SMOOTH);
gluQuadricOrientation(glQ, GLU_OUTSIDE);
gluQuadricTexture(glQ, GL_FALSE);
for (unsigned int y = 0; y < vSize; ++y) {
for (unsigned int x = 0; x < uSize; ++x) {
float xVal = 5*3.14/gridSize*x;
float yVal = 5*3.14/gridSize*y;
grid[y][x][0] = (float) x/gridSize*10.0;
grid[y][x][1] = sin(xVal + value) + sin(yVal + value);
grid[y][x][2] = (float) y/gridSize*10.0;
}
}
glMap2f(GL_MAP2_VERTEX_3, 0, 1 , 3, uSize, 0, 1, uSize * 3, vSize, &grid[0][0][0]);
glEvalMesh2(GL_FILL, 0, gridSize, 0, gridSize);
value += 3.14/25;
if (value > 3.14*2)
value = 0;
// swapping the buffers causes the rendering above to be shown
glutSwapBuffers();
glFlush();
}
/* Mouse handling */
void processMouse(int button, int state, int x, int y)
{
if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN)
{
}
if (button == GLUT_RIGHT_BUTTON && state == GLUT_DOWN)
{
}
glutPostRedisplay();
}
void processMouseMoved(int x, int y)
{
// pedido de refrescamento da janela
glutPostRedisplay();
}
void processPassiveMouseMoved(int x, int y)
{
// pedido de refrescamento da janela
glutPostRedisplay();
}
void reshape(int w, int h)
{
int tx, ty, tw, th;
GLUI_Master.get_viewport_area( &tx, &ty, &tw, &th );
glViewport( tx, ty, tw, th );
xy_aspect = (float)tw / (float)th;
glutPostRedisplay();
}
void keyboard(unsigned char key, int x, int y)
{
switch (key) {
case 27: // tecla de escape termina o programa
exit(0);
break;
}
}
void glut_idle( void )
{
if ( glutGetWindow() != main_window )
glutSetWindow(main_window);
glutPostRedisplay();
}
void init()
{
glQ = gluNewQuadric();
glFrontFace(GL_CCW); // Front faces defined using a counterclockwise rotation
glDepthFunc(GL_LEQUAL); // Por defeito e GL_LESS
glEnable(GL_DEPTH_TEST); // Use a depth (z) buffer to draw only visible objects
glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);
// Face Culling para aumentar a velocidade
glEnable(GL_CULL_FACE);
glCullFace(GL_BACK); // GL_FRONT, GL_BACK, GL_FRONT_AND_BACK
// Define que modelo de iluminacao utilizar; consultar o manual de referencia
glLightModelfv(GL_LIGHT_MODEL_AMBIENT, light_ambient); // define luz ambiente
glLightModelf (GL_LIGHT_MODEL_TWO_SIDE, GL_FALSE);
glLightModeli (GL_LIGHT_MODEL_LOCAL_VIEWER, 1);
// por defeito a cor de fundo e o preto
// glClearColor(1.0,1.0,1.0,1.0); // cor de fundo a branco
// declaracoes para a fonte luz GL_LIGHT0
glLightfv(GL_LIGHT0, GL_AMBIENT, light0_ambient);
glLightfv(GL_LIGHT0, GL_DIFFUSE, light0_diffuse);
glLightfv(GL_LIGHT0, GL_SPECULAR, light0_specular);
glLightf(GL_LIGHT0, GL_CONSTANT_ATTENUATION, light0_kc);
glLightf(GL_LIGHT0, GL_LINEAR_ATTENUATION, light0_kl);
glLightf(GL_LIGHT0, GL_QUADRATIC_ATTENUATION, light0_kq);
// NOTA: a direccao e a posicao de GL_LIGHT0 estao na rotina display(), pelo
// que as isntrucoes seguntes nao sao necessarias
//glLightf(GL_LIGHT0, GL_SPOT_CUTOFF, 90.0);
//glLightfv(GL_LIGHT0, GL_SPOT_DIRECTION, spot_direction);
//glLightfv(GL_LIGHT0, GL_POSITION, light0_position);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_NORMALIZE);
glEnable(GL_MAP2_VERTEX_3);
glMapGrid2f(gridSize, 0.0, 1.0, gridSize, 0.0, 1.0);
glShadeModel(GL_SMOOTH);
glPolygonMode(GL_FRONT, GL_FILL);
//glPolygonMode(GL_FRONT, GL_LINE);
}
void do_nothing(int key, int x, int y) {}
int main(int argc, char* argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
glutInitWindowSize (DIMX, DIMY);
glutInitWindowPosition (INITIALPOS_X, INITIALPOS_Y);
main_window = glutCreateWindow (argv[0]);
glutDisplayFunc(display);
GLUI_Master.set_glutReshapeFunc(reshape);
GLUI_Master.set_glutKeyboardFunc (keyboard);
GLUI_Master.set_glutMouseFunc(processMouse);
glutMotionFunc(processMouseMoved);
glutPassiveMotionFunc(processPassiveMouseMoved);
GLUI_Master.set_glutSpecialFunc( do_nothing );
/*** Create the bottom subwindow ***/
glui = GLUI_Master.create_glui_subwindow( main_window, GLUI_SUBWINDOW_BOTTOM );
glui->set_main_gfx_window( main_window );
GLUI_Rotation *view_rot = glui->add_rotation( "Rotation", view_rotate );
view_rot->set_spin( 1.0 );
glui->add_column( false );
GLUI_Translation *trans_z = glui->add_translation( "Zoom", GLUI_TRANSLATION_Z, &obj_pos[2] );
trans_z->set_speed( .1 );
glui->add_column(false);
GLUI_Translation *trans_pan = glui->add_translation("Pan", GLUI_TRANSLATION_XY, &obj_pan[0]);
trans_pan->set_speed(.1);
GLUI_Master.set_glutIdleFunc( glut_idle );
init();
glutMainLoop();
return 0;
}

Answer 1

You say OpenGL evaluators don't need normals to set. This is only partly true. You only don't need to set normals if you enable automatically generated normals for evaluators by calling:
glEnable(GL_AUTO_NORMAL);
Just enabling GL_NORMALIZE won't do it.
But you can of course also specify your own normals by providing control points for GL_MAP2_NORMAL in the same way like for GL_MAP2_VERTEX_3.
And the answer won't be complete without mentioning that OpenGL evaluators are highly deprecated and most probably implemented in softare by the driver. So just rolling your own Bezier evaluation code (which is not very hard) and generating a simple mesh grid drawn as GL_TRIANGLES will surely be a better idea.