How to change colors in OpenGL? - c++

Question

I want to color every part of the coordinate plane in different color (y in red, x in blue, z in green) but it seems that he remembers only the color of the lighting(red). So if someone can help me with that problem, i would be grateful.
#include <GL/glut.h>
//func
void setCamera();
void drawCP();
void drawPoints();
void drawCrtice();
GLfloat light_diffuse[] = {1.0, 0.0, .0, 0.0}; /* Red diffuse light. */
GLfloat light_position[] = {0.0, 0.0, 1.0, 0.0}; /* Infinite light location. */
GLfloat n[6][3] = {/* Normals for the 6 faces of a cube. */
{-1.0, 0.0, 0.0},
{0.0, 1.0, 0.0},
{1.0, 0.0, 0.0},
{0.0, -1.0, 0.0},
{0.0, 0.0, 1.0},
{0.0, 0.0, -1.0}
};
GLint faces[6][4] = {/* Vertex indices for the 6 faces of a cube. */
{0, 1, 2, 3},
{3, 2, 6, 7},
{7, 6, 5, 4},
{4, 5, 1, 0},
{5, 6, 2, 1},
{7, 4, 0, 3}
};
GLfloat v[8][3]; /* Will be filled in with X,Y,Z vertexes. */
void
drawBox(void) {
int i;
for (i = 0; i < 6; i++) {
glBegin(GL_QUADS);
glNormal3fv(&n[i][0]);
glVertex3fv(&v[faces[i][0]][0]);
glVertex3fv(&v[faces[i][1]][0]);
glVertex3fv(&v[faces[i][2]][0]);
glVertex3fv(&v[faces[i][3]][0]);
glEnd();
}
}
void
display(void) {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
drawBox();
drawCP();
glClearColor(0.6f, 0.6f, 0.6f, 1.0f);
glRotatef(0.2, 0, 5, 0);
glutPostRedisplay();
glutSwapBuffers();}
void
init(void) {
/* Setup cube vertex data. */
v[0][0] = v[1][0] = v[2][0] = v[3][0] = -1;
v[4][0] = v[5][0] = v[6][0] = v[7][0] = 1;
v[0][1] = v[1][1] = v[4][1] = v[5][1] = -1;
v[2][1] = v[3][1] = v[6][1] = v[7][1] = 1;
v[0][2] = v[3][2] = v[4][2] = v[7][2] = 1;
v[1][2] = v[2][2] = v[5][2] = v[6][2] = -1;
/* Enable a single OpenGL light. */
glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse);
glLightfv(GL_LIGHT0, GL_POSITION, light_position);
glEnable(GL_LIGHT0);
glEnable(GL_LIGHTING);
/* Use depth buffering for hidden surface elimination. */
glEnable(GL_DEPTH_TEST);
setCamera();}
void drawLines() {
glBegin(GL_LINES);
for (int i = 10; i != 0; i--) {
// po x osi
glVertex2f(-i, -0.1);
glVertex2f(-i, 0.1);
glVertex2f(i, -0.1);
glVertex2f(i, 0.1);
//po y osi
glVertex2f(-0.1, -i);
glVertex2f(0.1, -i);
glVertex2f(-0.1, i);
glVertex2f(0.1, i);
//po z osi
glColor3f(1.0f, 0.0f, 0.0f); //seems it doesnt register
glVertex3f(0, -0.3, -i);
glVertex3f(0, 0.3, -i);
glVertex3f(0, -0.3, i);
glVertex3f(0, 0.3, i);}
glEnd();}
void drawCP() {
//drawPoints();
drawLines();
glBegin(GL_LINES);
glLineWidth(100);
glVertex2f(-10.0f, 0);
glVertex2f(10.0f, 0);
glVertex2f(0.0f, 10);
glVertex2f(0.0f, -10);
glEnd();
}
void setCamera() {
/* Setup the view of the cube. */
glMatrixMode(GL_PROJECTION);
gluPerspective(/* field of view in degree */ 50.0, /* aspect ratio */ 1, /* Z near */ 1, /* Z far */ 100.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
/* Setup the view of the cube. */
gluLookAt(0, 0, 10 /*pozicija kamere*/, 0, 0, 0/* u koju tocku gleda ta kamera*/, 0, 1, 0 /*moran jos viti ca je to*/);
}
int
main(int argc, char **argv) {
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutCreateWindow("red 3D lighted cube");
glutDisplayFunc(display);
init();
// glutTimerFunc(10, rotate, 10);
glutMainLoop();
return 0; /* ANSI C requires main to return int. */
}

Answer 1

Try adding in: glEnable(GL_COLOR_MATERIAL);. That tells OpenGL your material properties are going to be defined with the glColor() function, it can be expanded on but that should get you what you expect.