OpenGL / GLUT照明没有意义

时间：2014-09-26 18:54:30

标签： c++ opengl glut

我的灯光有一些严重的问题，我认为我的数学是正确的，我正确定位每个顶点（逆时针），但结果仍然不正确。

是4个三角形，顶部有一个光源，当三角形关闭时一切都很好但是一旦它们打开，三角形内部的光线就会变得不正确。

任何帮助或提示？

enter image description here

enter image description here 

#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;
}

1 个答案:

答案 0 :(得分：2)

问题出在你的光位置数组lpos上。我假设你想要一个在所有方向发光的位置光，而不是仅在一个方向发光的定向光。对于位置光，lpos的第4分量应设置为1，对于定向光，该值应设置为0.对于任何值＆gt; 0，x，y和z值实际上除以第4个分量，因此当它设置为0.001时，灯光位置实际上并不是你想要的位置。

相关问题
最新问题