我正在使用allegro库和OpenGL。我启用深度测试,然后在调整大小时执行以下操作:
glEnable(GL_CULL_FACE);
glCullFace(GL_BACK);
glEnable(GL_DEPTH_TEST);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(0,event.display.width,event.display.height,0,1,300);
然后我的图像看起来像这样:
float BOX_SIZE = 200.0f;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glRotatef(0.5, 0, 0.0f, 1.0f);
glBegin(GL_QUADS);
//Top face
glColor3f(1.0f, 1.0f, 0.0f);
glNormal3f(0.0, 1.0f, 0.0f);
glVertex3f(500 + -BOX_SIZE / 2, BOX_SIZE / 2, -BOX_SIZE / 2);
glVertex3f(500 + -BOX_SIZE / 2, BOX_SIZE / 2, BOX_SIZE / 2);
glVertex3f(500 + BOX_SIZE / 2, BOX_SIZE / 2, BOX_SIZE / 2);
glVertex3f(500 + BOX_SIZE / 2, BOX_SIZE / 2, -BOX_SIZE / 2);
//Bottom face
glColor3f(1.0f, 0.0f, 1.0f);
glNormal3f(0.0, -1.0f, 0.0f);
glVertex3f(-BOX_SIZE / 2, -BOX_SIZE / 2, -BOX_SIZE / 2);
glVertex3f(BOX_SIZE / 2, -BOX_SIZE / 2, -BOX_SIZE / 2);
glVertex3f(BOX_SIZE / 2, -BOX_SIZE / 2, BOX_SIZE / 2);
glVertex3f(-BOX_SIZE / 2, -BOX_SIZE / 2, BOX_SIZE / 2);
//Left face
glNormal3f(-1.0, 0.0f, 0.0f);
glColor3f(0.0f, 1.0f, 1.0f);
glVertex3f(-BOX_SIZE / 2, -BOX_SIZE / 2, -BOX_SIZE / 2);
glVertex3f(-BOX_SIZE / 2, -BOX_SIZE / 2, BOX_SIZE / 2);
glColor3f(0.0f, 0.0f, 1.0f);
glVertex3f(-BOX_SIZE / 2, BOX_SIZE / 2, BOX_SIZE / 2);
glVertex3f(-BOX_SIZE / 2, BOX_SIZE / 2, -BOX_SIZE / 2);
//Right face
glNormal3f(1.0, 0.0f, 0.0f);
glColor3f(1.0f, 0.0f, 0.0f);
glVertex3f(BOX_SIZE / 2, -BOX_SIZE / 2, -BOX_SIZE / 2);
glVertex3f(BOX_SIZE / 2, BOX_SIZE / 2, -BOX_SIZE / 2);
glColor3f(0.0f, 1.0f, 0.0f);
glVertex3f(BOX_SIZE / 2, BOX_SIZE / 2, BOX_SIZE / 2);
glVertex3f(BOX_SIZE / 2, -BOX_SIZE / 2, BOX_SIZE / 2);
glEnd();
glEnable(GL_TEXTURE_2D);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glColor3f(1.0f, 1.0f, 1.0f);
glBegin(GL_QUADS);
//Front face
glNormal3f(0.0, 0.0f, 1.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-BOX_SIZE / 2, -BOX_SIZE / 2, BOX_SIZE / 2);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(BOX_SIZE / 2, -BOX_SIZE / 2, BOX_SIZE / 2);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(BOX_SIZE / 2, BOX_SIZE / 2, BOX_SIZE / 2);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-BOX_SIZE / 2, BOX_SIZE / 2, BOX_SIZE / 2);
//Back face
glNormal3f(0.0, 0.0f, -1.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-BOX_SIZE / 2, -BOX_SIZE / 2, -BOX_SIZE / 2);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(-BOX_SIZE / 2, BOX_SIZE / 2, -BOX_SIZE / 2);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(BOX_SIZE / 2, BOX_SIZE / 2, -BOX_SIZE / 2);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(BOX_SIZE / 2, -BOX_SIZE / 2, -BOX_SIZE / 2);
glEnd();
glDisable(GL_TEXTURE_2D);
//code goes here
al_flip_display();
由于某种原因,无论我如何翻译,立方体似乎总是从0,0延伸,并且始终存在一个顶点在0,0处。我做错了什么?谢谢。