我的照明有一些严重的问题，我认为我的数学是正确的并且我正确地定位了每个顶点(逆时针)，但结果仍然不正确。
有 4 个三角形，上面有一个光源，当三角形闭合时一切都很好，但是一旦它们打开，三角形内部的照明就会变得不正确。
任何帮助或提示？
#include <GL/glut.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#define PI 3.14159265
static int step = 0, step1, step2, step3, step4, step5, step6, step7, step8;
/* camera location in longitude and latitude */
static float alpha = 0.0;
static float beta = PI / 6.0;
/* position of camera */
static GLdouble cpos[3];
/* position of light source */
static GLfloat lpos[] = { 0,3,0, 0.001 };
/* vectors to specify material properties */
static GLfloat black[] = { 0.0, 0.0, 0.0, 1.0 };
static GLfloat white[] = { 1.0, 1.0, 1.0, 1.0 };
static GLfloat gray[] = { 0.5, 0.5, 0.5, 1.0 };
static GLfloat red[] = { 1.0, 0.0, 0.0, 1.0 };
static GLfloat green[] = { 0.0, 1.0, 0.0, 1.0 };
static GLfloat blue[] = { 0.0, 0.0, 1.0, 1.0 };
static GLfloat yellow[] = { 1.0, 1.0, 0.0, 1.0 };
static GLfloat magenta[] = { 1.0, 0.0, 1.0, 1.0 };
static GLfloat cyan[] = { 0.0, 1.0, 1.0, 1.0 };
static GLfloat darkcyan[] = { 0.0, 0.4, 0.4, 1.0 };
static GLfloat gold[] = { 255.0 / 255.0, 215.0 / 255.0, 0 / 255.0 };
static GLfloat silver[] = { 204.0 / 255.0, 204.0 / 255.0, 204.0 / 255.0 };
static bool trianglesExist = false;
static float stepBefore = step;
static float zoom = 10.0;
void writemessage()
{
printf("HW-1");
}
void init(void)
{
writemessage();
glClearColor(0.0, 0.0, 0.0, 0.0);
glEnable(GL_DEPTH_TEST);
glShadeModel(GL_SMOOTH);
/* initially GL_FILL mode (default), later GL_LINE to show wireframe */
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glEnable(GL_LIGHTING);
glLightModeli(GL_LIGHT_MODEL_TWO_SIDE, GL_TRUE);
glEnable(GL_LIGHT0);
}
void reshape(int w, int h)
{
glViewport(0, 0, (GLsizei)w, (GLsizei)h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(75.0, (GLfloat)w / (GLfloat)h, 1.0, 20.0);
glMatrixMode(GL_MODELVIEW);
}
void display(void)
{
static int i;
static double angle1, angle2, angle3, angle4, Y1, Z1, Y2, Z2, X3, Y3, X4, Y4;
static double angle5, angle6, angle7, angle8, X5, Y5, X6, Y6, X7, Y7, X8, Y8;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
/* initialize (modelview) matrix */
glLoadIdentity();
/* update camera position */
cpos[0] = zoom * cos(beta) * sin(alpha);
cpos[1] = zoom * sin(beta);
cpos[2] = zoom * cos(beta) * cos(alpha);
gluLookAt(cpos[0], cpos[1], cpos[2], 0.0, 1.0, 0.0, 0.0, 1.0, 0.0);
/* set current light source position */
glLightfv(GL_LIGHT0, GL_POSITION, lpos);
/* draw sphere to show light source */
glMaterialfv(GL_FRONT, GL_EMISSION, white);
glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, 128);
glPushMatrix();
glTranslatef(lpos[0], lpos[1], lpos[2]);
glutSolidSphere(0.1, 10, 8);
glPopMatrix();
/* remaining objects do not look as if they emit light */
glMaterialfv(GL_FRONT, GL_EMISSION, black);
/* draw a tabletop */
glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, darkcyan);
glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, white);
glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, 64);
glNormal3f(0.0, 1.0, 0.0);
glBegin(GL_POLYGON);
glVertex3f(-5.0, -0.001, -3.0);
glVertex3f(-5.0, -0.001, 5.0);
glVertex3f(5.0, -0.001, 5.0);
glVertex3f(5.0, -0.001, -3.0);
glEnd();
printf("%d", step);
printf("\n");
if (step <= 360)
trianglesExist = true;
else
trianglesExist = false;
if (step > 630 && step < 720){
step1 = 90;
step2 = 90;
step3 = 90;
step4 = 90;
step5 = 90;
step6 = 90;
step7 = 90;
step8 = step - 630;
}
else if (step > 540 && step < 720){
step1 = 90;
step2 = 90;
step3 = 90;
step4 = 90;
step5 = 90;
step6 = 90;
step7 = step - 540;
step8 = 0;
}
else if (step > 450 && step < 720){
step1 = 90;
step2 = 90;
step3 = 90;
step4 = 90;
step5 = 90;
step6 = step - 450;
step7 = 0;
step8 = 0;
}
else if (step > 360 && step < 720){
step1 = 90;
step2 = 90;
step3 = 90;
step4 = 90;
step5 = step - 360;
step6 = 0;
step7 = 0;
step8 = 0;
}
else if (step > 270 && step <= 360)
{
step1 = 90;
step2 = 90;
step3 = 90;
step4 = step - 270;
step5 = 0;
step6 = 0;
step7 = 0;
step8 = 0;
}
else if (step > 180 && step <= 360)
{
step1 = 90;
step2 = 90;
step3 = step - 180;
step4 = 0;
step5 = 0;
step6 = 0;
step7 = 0;
step8 = 0;
}
else if (step > 90 && step <= 360)
{
step1 = 90;
step2 = step - 90;
step3 = 0;
step4 = 0;
step5 = 0;
step6 = 0;
step7 = 0;
step8 = 0;
}
else if (step >= 0 && step <= 360)
{
step1 = step;
step2 = 0;
step3 = 0;
step4 = 0;
step5 = 0;
step6 = 0;
step7 = 0;
step8 = 0;
}
else;
// top back - first
glMaterialfv(GL_FRONT, GL_EMISSION, black);
glMaterialfv(GL_BACK, GL_EMISSION, black);
glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, gold);
glMaterialfv(GL_BACK, GL_AMBIENT_AND_DIFFUSE, silver);
glMaterialf(GL_BACK, GL_SHININESS, 128);
glMaterialf(GL_FRONT, GL_SHININESS, 128);
glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, white);
angle1 = ((float)step1 / 180) * PI;
glNormal3f(0, cos(angle1), -sin(angle1));
glBegin(GL_POLYGON);
glVertex3f(-3.0, 2.0, -1.0);
glVertex3f(0, 2.0 + 2.0 * sin(angle1), -1.0 + 2.0 * cos(angle1));
glVertex3f(3.0, 2.0, -1.0);
glEnd();
// top front - second
glMaterialfv(GL_FRONT, GL_EMISSION, black);
glMaterialfv(GL_BACK, GL_EMISSION, black);
glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, gold);
glMaterialfv(GL_BACK, GL_AMBIENT_AND_DIFFUSE, silver);
glMaterialf(GL_BACK, GL_SHININESS, 128);
glMaterialf(GL_FRONT, GL_SHININESS, 128);
glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, white);
angle2 = ((float)step2 / 180) * PI;
glNormal3f(0, cos(angle2), sin(angle2));
glBegin(GL_POLYGON);
glVertex3f(3.0, 2.0, 3.0);
glVertex3f(0, 2.0 + 2.0 * sin(angle2), 3.0 + -2.0 * cos(angle2));
glVertex3f(-3.0, 2.0, 3.0);
glEnd();
// top right - third
glMaterialfv(GL_FRONT, GL_EMISSION, black);
glMaterialfv(GL_BACK, GL_EMISSION, black);
glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, gold);
glMaterialfv(GL_BACK, GL_AMBIENT_AND_DIFFUSE, silver);
glMaterialf(GL_BACK, GL_SHININESS, 128);
glMaterialf(GL_FRONT, GL_SHININESS, 128);
glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, white);
angle3 = ((float)step3 / 180) * PI;
glNormal3f(sin(angle3), cos(angle3), 0);
glBegin(GL_POLYGON);
glVertex3f(3.0, 2.0, -1.0);
glVertex3f(3.0 - 3.0 * cos(angle3), 2.0 + 2.0 * sin(angle3), 1);
glVertex3f(3.0, 2.0, 3.0);
glEnd();
// top left - fourth
glMaterialfv(GL_FRONT, GL_EMISSION, black);
glMaterialfv(GL_BACK, GL_EMISSION, black);
glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, gold);
glMaterialfv(GL_BACK, GL_AMBIENT_AND_DIFFUSE, silver);
glMaterialf(GL_BACK, GL_SHININESS, 128);
glMaterialf(GL_FRONT, GL_SHININESS, 128);
glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, white);
angle4 = ((float)step4 / 180) * PI;
glNormal3f(-sin(angle4), cos(angle4), 0);
glBegin(GL_POLYGON);
glVertex3f(-3.0, 2.0, 3.0);
glVertex3f(-3.0 + 3.0 * cos(angle4), 2.0 + 2.0 * sin(angle4), 1);
glVertex3f(-3.0, 2.0, -1.0);
glEnd();
// buttom
glMaterialfv(GL_FRONT, GL_EMISSION, black);
glMaterialfv(GL_BACK, GL_EMISSION, black);
glMaterialfv(GL_BACK, GL_AMBIENT_AND_DIFFUSE, gold);
glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, silver);
glMaterialf(GL_BACK, GL_SHININESS, 128);
glMaterialf(GL_FRONT, GL_SHININESS, 128);
glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, white);
glBegin(GL_POLYGON);
glNormal3f(0, 1, 0);
glVertex3f(-3.0, 0.0, -1.0);
glVertex3f(-3.0, 0.0, 3.0);
glVertex3f(3.0, 0.0, 3.0);
glVertex3f(3.0, 0.0, -1.0);
glEnd();
glFlush();
glutSwapBuffers();
}
void keyboard(unsigned char key, int x, int y)
{
static int polygonmode[2];
switch (key) {
case 27:
exit(0);
break;
/* open and close the top */
case 'o':
if (step < 720) { stepBefore = step*1.0; step = step + 2; }
glutPostRedisplay();
break;
case 'c':
if (step > 0) {
stepBefore = step*1.0; step = step - 2;
}
glutPostRedisplay();
break;
/* w for switching between GL_FILL and GL_LINE
* Using a query command glGetIntegerv() we obtain two integers
* indicating the current GL_POLYGON_MODE for FRONT and BACK faces.
* Look up glIsEnabled() that may be found useful. */
case 'w':
glGetIntegerv(GL_POLYGON_MODE, polygonmode);
if (polygonmode[0] == GL_FILL)
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
else glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glutPostRedisplay();
break;
/* control lpos */
case 'x':
lpos[0] = lpos[0] + 0.2;
glutPostRedisplay();
break;
case 'X':
lpos[0] = lpos[0] - 0.2;
glutPostRedisplay();
break;
case 'y':
lpos[1] = lpos[1] + 0.2;
glutPostRedisplay();
break;
case 'Y':
lpos[1] = lpos[1] - 0.2;
glutPostRedisplay();
break;
case 'z':
lpos[2] = lpos[2] + 0.2;
glutPostRedisplay();
break;
case 'Z':
lpos[2] = lpos[2] - 0.2;
glutPostRedisplay();
break;
case '+':
if (zoom != 1.5)zoom = zoom - 0.5;
glutPostRedisplay();
break;
case '-':
zoom = zoom + 0.5;
glutPostRedisplay();
break;
default:
break;
}
}
void specialkey(GLint key, int x, int y)
{
switch (key) {
case GLUT_KEY_RIGHT:
alpha = alpha + PI / 180;
if (alpha > 2 * PI) alpha = alpha - 2 * PI;
glutPostRedisplay();
break;
case GLUT_KEY_LEFT:
alpha = alpha - PI / 180;
if (alpha < 0) alpha = alpha + 2 * PI;
glutPostRedisplay();
break;
case GLUT_KEY_UP:
if (beta < 0.45*PI) beta = beta + PI / 180;
glutPostRedisplay();
break;
case GLUT_KEY_DOWN:
if (beta > 0.05*PI) beta = beta - PI / 180;
glutPostRedisplay();
break;
default:
break;
}
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER, GL_TRUE);
glutInitWindowSize(800, 800);
glutInitWindowPosition(100, 100);
glutCreateWindow(argv[0]);
init();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutSpecialFunc(specialkey);
glutMainLoop();
return 0;
}
最佳答案
问题出在您的灯光位置阵列 lpos 上。我假设您想要一个向所有方向发光的定位灯，而不是一个只向一个方向发光的定向灯。对于位置光，lpos 的第 4 个分量应设置为 1，而对于定向光，该值应设置为 0。对于任何 > 0 的值，x、y 和 z 值实际上除以第 4 个分量，因此当它设置为 0.001，光线位置并不是您期望的位置。
关于c++ - OpenGL/GLUT 光照没有意义，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/26066453/