光追代码，定义了sdf物体：
@ti.dataclass
class SDFObject:
type: int
transform: Transform
material: Material
其中type表示形状，比如球，圆柱，圆面，方形平面等。
于是写了这样的函数：
@ti.func
def sdf_all(index: int, p: vec3, b: vec3) -> float:
result = MAX_DIS
if index == SHAPE.SPHERE:
result = sd_sphere(p, b)
elif index == SHAPE.BOX:
result = sd_box(p, b)
elif index == SHAPE.CYLINDER:
result = sd_cylinder(p, b)
elif index == SHAPE.CONE:
result = sd_cone(p, b)
elif index == SHAPE.PLANE_INFINITY:
result = sd_plane_infinity(p, b)
elif index == SHAPE.PLANE_CIRCLE:
result = sd_plane_circle(p, b)
elif index == SHAPE.PLANE_TRIANGLE:
result = sd_plane_triangle(p, b)
elif index == SHAPE.PLANE_TRIANGLE_R:
result = sd_plane_right_triangle(p, b)
elif index == SHAPE.PLANE_SQUARE:
result = sd_plane_square(p, b)
return result
这么多if分支，直接让我的耗时增加十倍百倍！
于是我想办法优化，先是用列表：
SHAPE_FUNC = [
sd_none,
sd_sphere,
sd_box,
sd_cylinder,
sd_cone,
sd_plane_infinity,
sd_plane_circle,
sd_plane_triangle,
sd_plane_right_triangle,
sd_plane_square
]
@ti.func
def sdf_all(index: int, p: vec3, b: vec3) -> float:
result = MAX_DIS
for i in ti.static(range(len(SHAPE_FUNC))):
if index == i:
result = ti.static(SHAPE_FUNC[i])(p, b)
return result
没有变化。
再尝试二分法：
@ti.func
def sdf_all(index: int, p: vec3, b: vec3) -> float:
result = MAX_DIS
# 二分查找式的分支，减少平均分支数
if index < 5:
if index < 3:
if index == 0:
result = sd_none(p, b)
elif index == 1:
result = sd_sphere(p, b)
else: # index == 2
result = sd_box(p, b)
else: # index >= 3 and index < 5
if index == 3:
result = sd_cylinder(p, b)
else: # index == 4
result = sd_cone(p, b)
else: # index >= 5
if index < 8:
if index == 5:
result = sd_plane_infinity(p, b)
elif index == 6:
result = sd_plane_circle(p, b)
else: # index == 7
result = sd_plane_triangle(p, b)
else: # index >= 8
if index == 8:
result = sd_plane_right_triangle(p, b)
else: # index == 9
result = sd_plane_square(p, b)
return result
性能有那么一丝丝的提升。
简直要疯了，该怎么办啊。我很确信就是这部分if太多导致的，因为我只使用两种形状，然后把不用的if形状注释掉，性能就回来了。