Question

我正在开发一个练习OpenGL程序。我基本上试图展示金字塔。我粘贴了迄今为止的代码。我遇到的问题是，当我打电话给gluLook时，我的屏幕变得完全黑了。这对我来说没有意义。我的金字塔有三角形，尺寸限制在一个大小（1,1,1）的盒子里，它位于原点。因此，如果我将眼睛放在远处的东西（10,10,10）并且看（0,0,0），为什么我看不到金字塔。当我注释掉gluLookAt时，我可以清楚地看到它。

#include <GL/glut.h>
#include <stdlib.h>
#include <stdio.h>

struct
{
    GLuint trifan;
    GLuint tribase;
    GLuint colors;
} b;

void display();
void init_buffer();
void check_errors();
void reshape(int w, int h);
void keyboard(unsigned char k, int x, int y);

int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitWindowSize(500, 500);
    glutCreateWindow("Pyramid");

    init_buffer();
    glutDisplayFunc(display);
    glutKeyboardFunc(keyboard);

    glutMainLoop();
}

void init_buffer()
{
    glGenBuffers(1, &(b.trifan));
    glBindBuffer(GL_ARRAY_BUFFER, b.trifan);

    GLfloat trifan[6][3] =
    {
        {0.0, 1.0, 0.0},
        {1.0, 0.0, 1.0},
        {-1.0, 0.0, 1.0},
        {-1.0, 0.0, -1.0},
        {1.0, 0.0, -1.0},
        {1.0, 0.0, 1.0}
    };

    glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat) * 3 * 6, trifan, GL_STATIC_COPY);

    glGenBuffers(1, &b.colors);
    glBindBuffer(GL_ARRAY_BUFFER, b.colors);

    GLfloat colors[6][3] = 
    {
            {1.0, 0.0, 0.0},
            {1.0, 0.0, 0.0},
            {1.0, 0.0, 0.0},
            {1.0, 0.0, 1.0},
            {0.5, 0.0, 1.0},
            {1.0, 0.0, 0.5},
    };
    glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat) * 3 * 6, colors, GL_STATIC_COPY);

    check_errors();
}

void reshape(int w, int h)
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(60, (float)w / (float)h, 1.0, 100.0);
}

float angle = 0.0;
float zoom = 1.0;
void keyboard(unsigned char k, int x, int y)
{
    if(k == 'x')
    {
        angle += 10;
    }
    else if(k == 'y')
    {
        angle -= 10;
    }
    else if(k == 'w')
    {
        zoom += 0.1;
    }
    else if(k == 's')
    {
        zoom -= 0.1;
    }

    glutPostRedisplay();
}

void display()
{
    glClear(GL_COLOR_BUFFER_BIT);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glRotated(angle, 1.0, 0.0, 0.0);
    gluLookAt(10.0, 10.0, 10.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);

    glEnableClientState(GL_COLOR_ARRAY);
    glEnableClientState(GL_VERTEX_ARRAY);
    {
        glBindBuffer(GL_ARRAY_BUFFER, b.trifan);
        glVertexPointer(3, GL_FLOAT, 0, 0);

        glBindBuffer(GL_ARRAY_BUFFER, b.colors);
        glColorPointer(3, GL_FLOAT, 0, 0);

        glDrawArrays(GL_TRIANGLE_FAN, 0, 6);
    }
    glDisableClientState(GL_COLOR_ARRAY);
    glDisableClientState(GL_VERTEX_ARRAY);

    check_errors();
    glFlush();
}

void check_errors()
{
    GLint err = glGetError();
    if(err != GL_NO_ERROR)
    {
        fputs((char*)gluErrorString(err), stderr);
        exit(1);
    }
}

当gluLookAt调用时，OpenGL不显示任何内容

0 个答案: