[OpenGL] 一个小demo1

#include

static GLfloat xRot = 0.0f;
static GLfloat yRot = 0.0f;
bool bwinding = true;

void init() {
	glClearColor(0, 0, 0, 0);
}

void reshape(int w, int h) {
	if (h == 0) h = 1;
	glViewport(0, 0, w, h);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	if (w <= h) {
		glOrtho(-100, 100, -100 * h / w, 100 * h / w, -100, 100);
	}
	else {
		glOrtho(-100, 100, -100 * w / h, 100 * w / h, -100, 100);
	}
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
}

void display(void) {
	glClear(GL_COLOR_BUFFER_BIT);
	glPushMatrix();
	glRotatef(xRot, 1, 0, 0);
	glRotatef(yRot, 0, 1, 0);

	glPointSize(5);
	glLineWidth(5);

	if (bwinding) {
		glFrontFace(GL_CW);
	}
	else {
		glFrontFace(GL_CCW);
	}

	glBegin(GL_TRIANGLES);
	glColor3f(0, 1, 0);
	glVertex3f(0, 60, 0);
	glColor3f(1, 0, 0);
	glVertex3f(-60, -60, 0);
	glColor3f(0, 0, 1);
	glVertex3f(60, -60, 0);
	glEnd();
	glPopMatrix();
	glutSwapBuffers();
}

void specialKeys(int key, int x, int y) {
	if (key == GLUT_KEY_UP) xRot -= 5.0f;
	if (key == GLUT_KEY_DOWN) xRot += 5.0f;
	if (key == GLUT_KEY_LEFT) yRot -= 5.0f;
	if (key == GLUT_KEY_RIGHT) yRot += 5.0f;

	if (xRot > 356.0f) xRot = 0;
	if (yRot > 356.0f) yRot = 0;
	if (xRot < -1.0f) xRot = 355;
	if (yRot < -1.0f) yRot = 355;

	glutPostRedisplay();

}

void ProcessMenu(int value) {
	switch(value) {
	case 1: glPolygonMode(GL_FRONT, GL_FILL);
		break;
	case 2: glPolygonMode(GL_FRONT, GL_LINE);
		break;
	case 3: glPolygonMode(GL_FRONT, GL_POINT);
		break;
	case 4: glPolygonMode(GL_BACK, GL_FILL);
		break;
	case 5:glPolygonMode(GL_BACK, GL_LINE);
		break;
	case 6:glPolygonMode(GL_BACK, GL_POINT);
		break;
	case 7: glShadeModel(GL_FLAT);
		break;
	case 8: glShadeModel(GL_SMOOTH);
		break;
	case 9:bwinding = !bwinding;
		break;
	default: break;
	}
	glutPostRedisplay();
}



int main(int argc, char** argv) {
	int nModeMenu;
	int nMainMenu;
	int nColorMenu;

	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
	glutCreateWindow("多边形演示");
	glutReshapeFunc(reshape);
	glutSpecialFunc(specialKeys);
	glutDisplayFunc(display);

	nModeMenu = glutCreateMenu(ProcessMenu);
	glutAddMenuEntry("正面多边形填充模式", 1);
	glutAddMenuEntry("正面线框模型", 2);
	glutAddMenuEntry("正面点模型", 3);
	glutAddMenuEntry("反面多边形填充模式", 4);
	glutAddMenuEntry("反面相框模型", 5);
	glutAddMenuEntry("反面点模型", 6);

	nColorMenu = glutCreateMenu(ProcessMenu);
	glutAddMenuEntry("平面明暗模式", 7);
	glutAddMenuEntry("光滑敏感模式", 8);

	nMainMenu = glutCreateMenu(ProcessMenu);
	glutAddSubMenu("多边形模式", nModeMenu);
	glutAddSubMenu("颜色模式", nColorMenu);
	glutAddMenuEntry("改变绕法", 9);

	glutAttachMenu(GLUT_RIGHT_BUTTON);
	init();
	glutMainLoop();
	return 0;
}