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我的最后一项工作包括在我已经制作的圆的中心添加一个带有纹理的 3D 立方体，但由于某种原因，屏幕只是显示为黑色，没有数字或任何东西；我知道这可能是我在错误的地方添加的东西或类似的东西，但我不知道究竟是哪个部分给出了错误。这个问题有什么解释吗？

#include"glut.h"
#include<cmath>
#include<iostream>
using namespace std;

GLfloat angle = 0.0f;
int refreshmill = 1;

float xr = 0, yr = 0; //to control the object's movement from left to right

// XZ position of the camera
float x = 0.0f, z = 5.0f; //Module 4
float angleX = 0.0f; //Module 4

//Shift + ArrowKey rotation
float transX = 0.0f;
float transY = 0.0f;
float rotY = 0.0f;
//end

//Mouse Commands
GLfloat theta3 = 0;
GLfloat phi = 0;
GLfloat rho = 5;

GLfloat camX = 0;
GLfloat camY = 0;
GLfloat camZ = 0;
GLfloat upX = 0;
GLfloat upY = 0;
GLfloat upZ = 0;

GLdouble zoom = 0.0f;
//end

//For cube usage
#define checkImageWidth 64
#define checkImageHeight 64
static GLubyte checkImage[checkImageHeight][checkImageWidth][4];

static GLuint texName;

void timer(int value) { //to control the rotation of the object
    glutTimerFunc(refreshmill, timer, 0);
}

void myDisplay(void) {
    //Circle One
    float theta;
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1, 0, 0);

    glRotatef(rotY, 0.0, 1.0, 0.0); //Rotation with Shift + ArrowKey

    glPushMatrix();
    glBegin(GL_POLYGON);
    for (int x = 0; x < 360; x++) {
        theta = x * 3.142 / 180;
        glVertex2f(150 * cos(theta) + xr, 150 * sin(theta) + yr);
    }
    glEnd();
    glPopMatrix();

    //Circle Two
    float theta2;

    glPushMatrix();
    glTranslatef(0.5f, 0.0f, 0.0f); // rotation
    glRotatef(angle, 0.0f, 0.0f, -0.5f); // rotation
    glBegin(GL_POLYGON);
    glColor3f(0, 0, 1);
    for (int x = 0; x < 360; x++) {
        theta2 = x * 3.142 / 180;
        glVertex2f(150 + 15 * cos(theta2) + xr, 15 * sin(theta2) + yr);
    }

    angle += 0.2; // rotation
    glEnd();
    glPopMatrix();

    //Draw Star
    glColor3ub(119, 193, 15);

    glPushMatrix();
    glBegin(GL_POLYGON);
    glVertex2d(15 + xr, 60 + yr);
    glVertex2d(75 + xr, 75 + yr); //right peak
    glVertex2d(15 + xr, 90 + yr);
    glVertex2d(0 + xr, 150 + yr); //Up-peak Changed
    glVertex2d(-15 + xr, 90 + yr);
    glVertex2d(-75 + xr, 75 + yr);
    glVertex2d(-15 + xr, 60 + yr);
    glVertex2d(0 + xr, 0 + yr);
    glEnd();
    glPopMatrix();

    //Draw cube
    glPushMatrix();
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glEnable(GL_TEXTURE_2D);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); //DECAL & MODULATE
    glBindTexture(GL_TEXTURE_2D, texName);
    glBegin(GL_QUADS);
    // Front Face
    glColor3f(1.0, 1.0, 0.0); //yellow
    glTexCoord2f(0.0f, 0.0f); glVertex3f(-0.25f, -0.25f, 0.25f);
    glTexCoord2f(1.0f, 0.0f); glVertex3f(0.25f, -0.25f, 0.25f);
    glTexCoord2f(1.0f, 1.0f); glVertex3f(0.25f, 0.25f, 0.25f);
    glTexCoord2f(0.0f, 1.0f); glVertex3f(-0.25f, 0.25f, 0.25f);
    // Back Face
    glColor3f(0.0, 1.0, 1.0); //cyn
    glTexCoord2f(1.0f, 0.0f); glVertex3f(-0.25f, -0.25f, -0.25f);
    glTexCoord2f(1.0f, 1.0f); glVertex3f(-0.25f, 0.25f, -0.25f);
    glTexCoord2f(0.0f, 1.0f); glVertex3f(0.25f, 0.25f, -0.25f);
    glTexCoord2f(0.0f, 0.0f); glVertex3f(0.25f, -0.25f, -0.25f);
    // Top Face
    glColor3f(1.0, 0.0, 1.0); //mag side
    glTexCoord2f(0.0f, 1.0f); glVertex3f(-0.25f, 0.25f, -0.25f);
    glTexCoord2f(0.0f, 0.0f); glVertex3f(-0.25f, 0.25f, 0.25f);
    glTexCoord2f(1.0f, 0.0f); glVertex3f(0.25f, 0.25f, 0.25f);
    glTexCoord2f(1.0f, 1.0f); glVertex3f(0.25f, 0.25f, -0.25f);
    // Bottom Face
    glColor3f(1.0, 0.0, 0.0); //red
    glTexCoord2f(1.0f, 1.0f); glVertex3f(-0.25f, -0.25f, -0.25f);
    glTexCoord2f(0.0f, 1.0f); glVertex3f(0.25f, -0.25f, -0.25f);
    glTexCoord2f(0.0f, 0.0f); glVertex3f(0.25f, -0.25f, 0.25f);
    glTexCoord2f(1.0f, 0.0f); glVertex3f(-0.25f, -0.25f, 0.25f);
    // Right face
    glColor3f(0.0, 0.0, 1.0); //bue
    glTexCoord2f(1.0f, 0.0f); glVertex3f(0.25f, -0.25f, -0.25f);
    glTexCoord2f(1.0f, 1.0f); glVertex3f(0.25f, 0.25f, -0.25f);
    glTexCoord2f(0.0f, 1.0f); glVertex3f(0.25f, 0.25f, 0.25f);
    glTexCoord2f(0.0f, 0.0f); glVertex3f(0.25f, -0.25f, 0.25f);
    // Left Face
    glColor3f(0.0, 1.0, 0.0); //green
    glTexCoord2f(0.0f, 0.0f); glVertex3f(-0.25f, -0.25f, -0.25f);
    glTexCoord2f(1.0f, 0.0f); glVertex3f(-0.25f, -0.25f, 0.25f);
    glTexCoord2f(1.0f, 1.0f); glVertex3f(-0.25f, 0.25f, 0.25f);
    glTexCoord2f(0.0f, 1.0f); glVertex3f(-0.25f, 0.25f, -0.25f);

    glEnd();
    glDisable(GL_TEXTURE_2D);
    glPopMatrix();
}

void makeCheckImage(void){
    int i, j, c;

    for (i = 0; i < checkImageHeight; i++) {
        for (j = 0; j < checkImageWidth; j++) {
            c = ((((i & 0x8) == 0) ^ ((j & 0x8)) == 0)) * 255;
            checkImage[i][j][0] = (GLubyte)c;
            checkImage[i][j][1] = (GLubyte)c;
            checkImage[i][j][2] = (GLubyte)c;
            checkImage[i][j][3] = (GLubyte)255;
        }
    }
}

//Close code
void handleKeypress(unsigned char key, int x, int y) {
    switch (key) {
    case 27: //when the escape key is pressed the program will exit.
        exit(0);
    }
}

//Movement of drawing
void keyboard(int key, int x, int y) {

    float fraction = 0.1f;
    bool shift = false;
    int mod = glutGetModifiers();
    if (mod == GLUT_ACTIVE_SHIFT) {
        shift = true;
    }
    if (!shift) {
        switch (key) {

        case GLUT_KEY_RIGHT: xr++; break;
        case GLUT_KEY_LEFT:  xr--; break;
        case GLUT_KEY_UP:    angleX -= 1.0f; break; //Module 4
        case GLUT_KEY_DOWN:  angleX += 1.0f; break; //Module 4
        }
    }
    else {
        switch (key) {

        case GLUT_KEY_LEFT:// Rotación del dibujo hacia la izquierda en el eje de Y
            rotY -= 1.0f;
            break;
        case GLUT_KEY_RIGHT:// Rotación del dibujo hacia la derecha en el eje de Y
            rotY += 1.0f;
            break;
        }
    }
}

//Mouse Function
void MouseFunc(int button, int state, int x, int y) {

    GLdouble min_z = -100.0;
    GLdouble max_z = 100.0;

    if (button == 4 && zoom < max_z) {
        zoom += 3.0;
    }
    else if (button == 3 && zoom > min_z) {
        zoom -= 3.0;
    }
}

void renderScene(void) {
    // Clear Color and Depth Buffers
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    GLfloat camX = rho * cos(theta3*3.1415926f / 180)*sin(phi*3.1415926f / 180);
    GLfloat camY = rho * sin(theta3*3.1415926f / 180);
    GLfloat camZ = rho * cos(theta3*3.1415926f / 180)*cos(phi*3.1415926f / 180);

    // Reduce theta slightly to obtain another point on the same longitude line on the sphere.
    GLfloat dt = 1;
    GLfloat eyeXtemp = -rho * cos((theta3 - dt)*3.1415926f / 180)*sin(phi*3.1415926f / 180);
    GLfloat eyeYtemp = -rho * sin((theta3 - dt)*3.1415926f / 180);
    GLfloat eyeZtemp = -rho * cos((theta3 - dt)*3.1415926f / 180)*cos(phi*3.1415926f / 180);

    // Connect these two points to obtain the camera's up vector.
    GLfloat upX = eyeXtemp - camX;
    GLfloat upY = eyeYtemp - camY;
    GLfloat upZ = eyeZtemp - camZ;

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    //Mouse Commands
    GLdouble ortho = 250 + zoom; //Mouse wheel zoom
    glOrtho(-ortho, ortho, -ortho, ortho, -250, 250); //Mouse wheel zoom

    // Reset transformations
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    gluLookAt(camX, camY, camZ, 0, 0, 0, upX, upY, upZ);

    // Set the camera
    gluLookAt(x, 0.0f, z, x, 0.0f, z - 1.0f, 0.0f, 1.0f, 0.0f); //Module 4
    glRotatef(angleX, 1, 0, 0); //Module 4

    myDisplay();
    //DrawCube(0.0f, 0.0f, 0.85);

    glFlush();
    glutPostRedisplay();
    glutSwapBuffers();
}

void init() {
    glClearColor(0, 0, 0, 1);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(0.0f, 0.1f, 0.1f, 100.0f);
    glOrtho(-250, 250, -250, 250, -250, 250); //IMPORTANT- Define from negative to positive
    glMatrixMode(GL_MODELVIEW);

    //CUBE COMMANDS
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glShadeModel(GL_FLAT);
    glEnable(GL_DEPTH_TEST);

    makeCheckImage();
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

    glGenTextures(1, &texName);
    glBindTexture(GL_TEXTURE_2D, texName);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,
        GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
        GL_NEAREST);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, checkImageWidth,
        checkImageHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE,
        checkImage);
}

int main(int argc, char** argv) {
    // init GLUT and create window
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(500, 500);
    glutInitWindowPosition(0, 0);
    glutCreateWindow("Homework: Circle");
    // register callbacks
    glutDisplayFunc(renderScene);
    glutTimerFunc(0, timer, 0);
    glutKeyboardFunc(handleKeypress);
    glutSpecialFunc(keyboard);
    glutMouseFunc(MouseFunc);
    // OpenGL init
    init();
    // enter GLUT event processing cycle
    glutMainLoop();
}
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1 回答 1

1

在使用纹理绘制网格之前，第二次清除视口。

带有纹理的网格的顶点坐标在 [0, 1] 范围内，但在大小为 500x500 的视口上，正交投影在 [-250, 250] 范围内。所以网格的大小是 1 个像素。

用于glScale增加带有纹理的网格的大小：

例如

glPushMatrix();

// rotate the model (this is optional)
glRotatef(45, 0, 1, 0);
glRotatef(45, 1, 0, 0);

// scale the model
glScalef(200.0f, 200.0f, 200.0f);

//glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // <--- delete

glEnable(GL_TEXTURE_2D);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); //DECAL & MODULATE
glBindTexture(GL_TEXTURE_2D, texName);
glBegin(GL_QUADS);

// [...]

glEnd();
glDisable(GL_TEXTURE_2D);

请注意，深度测试已启用 ( glEnable(GL_DEPTH_TEST);)，因此几何体的某些部分不可见，因为它被其他几何体覆盖。

于 2019-05-03T17:06:11.053 回答