如何在opengl中绘制y轴或x轴上的圆柱体

Question

我只想在opengl中画一个圆柱体。我找到了很多样本，但它们都在z轴上画圆柱体。我想让它们在x或y轴上。我怎么能这么做呢?下面的代码是在z方向绘制圆柱体的代码，我不想让它

  GLUquadricObj *quadratic;
  quadratic = gluNewQuadric();
  gluCylinder(quadratic,0.1f,0.1f,3.0f,32,32);

Answer 1

你可以使用glRotate(angle, x, y, z)来旋转你的坐标系:

GLUquadricObj *quadratic;
quadratic = gluNewQuadric();
glRotatef(90.0f, 0.0f, 1.0f, 0.0f);
gluCylinder(quadratic,0.1f,0.1f,3.0f,32,32);

http://www.opengl.org/sdk/docs/man/xhtml/glRotate.xml

Answer 2

每次渲染时使用glPushMatrix glRotatef绘制圆柱体，并使用glPopMatrix完成绘图。

交货。: glRotatef(yRotationAngle, 0.0f, 1.0f, 0.0f); // Rotate your object around the y axis on yRotationAngle radians

交货。: OnRender()函数示例

void OnRender() {
  glClearColor(1.0f, 0.0f, 0.0f, 1.0f); // Clear the background
  glClear(GL_COLOR_BUFFER_BIT); //Clear the colour buffer
  glLoadIdentity(); // Load the Identity Matrix to reset our drawing locations
  glRotatef(yRotationAngle, 0.0f, 1.0f, 0.0f); // Rotate our object around the y axis on yRotationAngle radians
  // here *render* your cylinder (create and delete it in the other place. Not while rendering)
  gluCylinder(quadratic,0.1f,0.1f,3.0f,32,32);
  glFlush(); // Flush the OpenGL buffers to the window  
}