vec: remove the useless swizzles in the last argument #253
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If the last argument of a vector is `foo.x`, `foo.xy`, `foo.xyz` or `foo.xyzw`, replace it with just `foo`. According to the spec, components are used from left to right, and additional components are ignored.
jwatzman
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Apr 16, 2023
The optimization in laurentlb#253 is unsafe -- `vec3(a.x)` and `vec3(x)` are not equivalent. For a single-element swizzles, they are only sure to be safe if they are the Nth argument to a vecN constructor. This change counts the number of arguments, and only allows a single-element swizzle to be optimized in that case. This does miss some edge cases -- for example, I think the swizzle in code like `vec3(foo.xy, bar.x)` is safe to remove (`vec3(foo.xy, bar)`) but that doesn't seem to actually happen in any of the examples in this repo, and it's super tricky to get right in practise (if `foo.xy` is some variable instead of a swizzle right there), etc etc. So there is potentially still something on the table, but at least for the cases available this is good enough for now. Fixes laurentlb#297
laurentlb
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Apr 17, 2023
The optimization in laurentlb#253 is unsafe -- `vec3(a.x)` and `vec3(x)` are not equivalent. For a single-element swizzles, they are only sure to be safe if they are the Nth argument to a vecN constructor. This change counts the number of arguments, and only allows a single-element swizzle to be optimized in that case. This does miss some edge cases -- for example, I think the swizzle in code like `vec3(foo.xy, bar.x)` is safe to remove (`vec3(foo.xy, bar)`) but that doesn't seem to actually happen in any of the examples in this repo, and it's super tricky to get right in practise (if `foo.xy` is some variable instead of a swizzle right there), etc etc. So there is potentially still something on the table, but at least for the cases available this is good enough for now. Fixes laurentlb#297
laurentlb
pushed a commit
that referenced
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Apr 17, 2023
The optimization in #253 is unsafe -- `vec3(a.x)` and `vec3(x)` are not equivalent. For a single-element swizzles, they are only sure to be safe if they are the Nth argument to a vecN constructor. This change counts the number of arguments, and only allows a single-element swizzle to be optimized in that case. This does miss some edge cases -- for example, I think the swizzle in code like `vec3(foo.xy, bar.x)` is safe to remove (`vec3(foo.xy, bar)`) but that doesn't seem to actually happen in any of the examples in this repo, and it's super tricky to get right in practise (if `foo.xy` is some variable instead of a swizzle right there), etc etc. So there is potentially still something on the table, but at least for the cases available this is good enough for now. Fixes #297
laurentlb
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that referenced
this pull request
Apr 30, 2023
The optimization in #253 is unsafe -- `vec3(a.x)` and `vec3(x)` are not equivalent. For a single-element swizzles, they are only sure to be safe if they are the Nth argument to a vecN constructor. This change counts the number of arguments, and only allows a single-element swizzle to be optimized in that case. This does miss some edge cases -- for example, I think the swizzle in code like `vec3(foo.xy, bar.x)` is safe to remove (`vec3(foo.xy, bar)`) but that doesn't seem to actually happen in any of the examples in this repo, and it's super tricky to get right in practise (if `foo.xy` is some variable instead of a swizzle right there), etc etc. So there is potentially still something on the table, but at least for the cases available this is good enough for now. Fixes #297
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If the last argument of a vector is
foo.x,foo.xy,foo.xyzorfoo.xyzw, replace it with justfoo.According to the spec, components are used from left to right, and additional components are ignored.
Examples: