三維圖形變換
模型變換
問題:透視投影矩陣?
透視變換規則:
利用相似三角形定理
背面剔除:
glMatrixMode (GL_MODELVIEW);
glLoadIdentity ();
gluLookAt ( eye.x , eye.y , eye.z , look.x ,
look.y , look.z , up.x , up.y , up.z );
glOrtho (left, right, bottom, top, near, far);
或者 : glOrtho2D (left, right, bottom, top);
glMatrixMode (GL_PROJECTION);
glLoadIdentity ( );
glOrtho (left, right, bottom, top, near, far)
glFrustum (left, right, bottom, top, near, far)
glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
glFrustum (left, right, bottom, top,
near, far)
glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
gluPerspective (angle, aspect, near, far)
glViewport ( GLint left, GLint bottom, GLint width,
GLint height)