我想要解决的任务很简单:加载一个纹理化的OBJ文件并显示它,使其占用最大量的图像空间。只要照相机向下看z轴的负方向而y轴是向上向量,就不需要旋转网格。我正在使用pyglet来做到这一点。为了将相机设置到所需的位置,我正在做以下操作(代码见下面):计算网格的边界球体,网格的边界球体由网格中心定义,半径为离最远的点中心。然后我按照例如的说明来计算平截头体here,并据此设置正交投影。然后,我使用gluLookAt
来更新modelviewmatrix,如下所示:摄像机位于正z轴上,朝向网格中心,y轴是向上矢量。为什么我的渲染图像没有显示我期望看到使用gluLookAt的视图?
问题是我的渲染图像看起来并不像我期望的那样,例如,网格的中心不在图像的中心,如下图所示。图像显示边界框和源自计算的网格中心的坐标轴(红色:x轴,绿色:y轴,蓝色:z轴)。
来设置相机的代码是:
# get the bounding sphere
center, radius = self._mesh.compute_bounding_sphere()
diam = radius*2.0
print 'center:'
print center
print 'radius: %f' % radius
# set up near and far clipping plane
z_near = 1.0
z_far = z_near + diam
# construct params for orthographic projection matrix
left = center[0] - radius
right = center[0] + radius
bottom = center[1] - radius
top = center[1] + radius
# if we are not rendering a square image, must correct for aspect ratio
aspect_ratio = float(self.width)/float(self.height)
if aspect_ratio < 1.0:
bottom /= aspect_ratio
top /= aspect_ratio
else:
left *= aspect_ratio
right *= aspect_ratio
print 'znear %f, zfar %f' % (z_near, z_far)
print 'left %f, right %f' % (left, right)
print 'bottom %f, top %f' % (bottom, top)
# specify a parallel projection with clipping planes as computed above
glMatrixMode(GL_PROJECTION)
glLoadIdentity()
glOrtho(left, right, bottom, top, z_near, z_far)
# gluPerspective(50.0, aspect_ratio, z_near, z_far)
# construct a viewing transform as follows: we look at the center of the mesh, the eye is located on the
# positive z-axis, and the 3D y-axis is the up-vector, i.e. it will be mapped to the y-axis in image space.
eye = center[2] + radius
print 'eye:'
print eye
glMatrixMode(GL_MODELVIEW)
glLoadIdentity()
gluLookAt(0.0, 0.0, eye, center[0], center[1], center[2], 0.0, 1.0, 0.0)
它打印
center:
[ 8.51203675 -1.95199815 0.35396978]
radius: 10.462382
znear 1.000000, zfar 21.924764
left -1.950345, right 18.974419
bottom -12.414380, top 8.510384
eye:
10.8163515441
你能不能帮我鉴定一下我做错了吗?