open gl 渐变立方体

可以使用OpenGL来创建渐变立方体。以下是一个使用OpenGL和GLSL（OpenGL Shading Language）的示例代码来实现渐变立方体的基本效果：

#include <GL/glut.h>

GLfloat vertices[] = {
    -1.0f, -1.0f, -1.0f,
    1.0f, -1.0f, -1.0f,
    1.0f, 1.0f, -1.0f,
    -1.0f, 1.0f, -1.0f,
    -1.0f, -1.0f, 1.0f,
    1.0f, -1.0f, 1.0f,
    1.0f, 1.0f, 1.0f,
    -1.0f, 1.0f, 1.0f
};

GLfloat colors[] = {
    1.0f, 0.0f, 0.0f,
    0.0f, 1.0f, 0.0f,
    0.0f, 0.0f, 1.0f,
    1.0f, 1.0f, 0.0f,
    1.0f, 0.0f, 1.0f,
    0.0f, 1.0f, 1.0f,
    0.5f, 0.5f, 0.5f,
    1.0f, 1.0f, 1.0f
};

GLubyte indices[] = {
    0, 3, 2, 1,
    2, 3, 7, 6,
    0, 4, 7, 3,
    1, 2, 6, 5,
    4, 5, 6, 7,
    0, 1, 5, 4
};

void display() {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();
    gluLookAt(0.0f, 0.0f, 8.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f);

    glEnableClientState(GL_VERTEX_ARRAY);
    glEnableClientState(GL_COLOR_ARRAY);

    glVertexPointer(3, GL_FLOAT, 0, vertices);
    glColorPointer(3, GL_FLOAT, 0, colors);

    glDrawElements(GL_QUADS, 24, GL_UNSIGNED_BYTE, indices);

    glDisableClientState(GL_VERTEX_ARRAY);
    glDisableClientState(GL_COLOR_ARRAY);

    glutSwapBuffers();
}

void reshape(int width, int height) {
    glViewport(0, 0, width, height);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45.0f, (GLfloat)width / (GLfloat)height, 0.1f, 100.0f);
    glMatrixMode(GL_MODELVIEW);
}

int main(int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);    glutInitWindowSize(800, 600);
    glutCreateWindow("Gradient Cube");
    glutDisplayFunc(display);    glutReshapeFunc(reshape);
    glEnable(GL_DEPTH_TEST);
    glutMainLoop();
    return 0;
}

这段代码使用了OpenGL的固定管线（Fixed Function Pipeline）来绘制一个带有颜色渐变的立方体。立方体的顶点坐标存储在`vertices`数组中，每个顶点对应的颜色存储在`colors`数组中，立方体的面索引存储在`indices`数组中。`display`函数用于绘制立方体，`reshape`函数用于处理窗口大小改变时的透视投影变换。