GPU: Add explicit matrix constructor #119031

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Clément Foucault · 2024-03-03T16:10:42+01:00

Clément Foucault commented

2024-03-03 16:10:42 +01:00

MSL doesn't support as much constructor for matrices as GLSL. This creates some error prone situation where only some constructors are added on the MSL side.
Moreover, MSL need string replacement to support these non-native constructors, which slows compilation down.

While the string replacement is still needed for PyGPU shader (for compatibility reason) we can avoid this for internal shaders.

Proposal

Add explicit constructors in both GLSL and MSL with something like float3x3 make_float3x3(float3 a, float3 b, float3 c) and only declare a small set of constructors (no mixed scalar / vector constructor). I chose to use cycles convention of make_*.
Prohibit usage of builtin constructor (after removing existing usages) by using something like #define mat3() do_not_use.

MSL doesn't support as much constructor for matrices as GLSL. This creates some error prone situation where only some constructors are added on the MSL side. Moreover, MSL need string replacement to support these non-native constructors, which slows compilation down. While the string replacement is still needed for PyGPU shader (for compatibility reason) we can avoid this for internal shaders. ### Proposal - Add explicit constructors in both GLSL and MSL with something like `float3x3 make_float3x3(float3 a, float3 b, float3 c)` and only declare a small set of constructors (no mixed scalar / vector constructor). I chose to use cycles convention of `make_*`. - Prohibit usage of builtin constructor (after removing existing usages) by using something like `#define mat3() do_not_use`.

Clément Foucault added the

labels 2024-03-03 16:10:42 +01:00

Miguel Pozo commented

2024-03-04 17:00:52 +01:00

What types of matrix constructors are supported/unsupported in MSL?

If possible, I would do this only for non supported constructors.

So we still can use:
mat3 m = mat3(i, j, k);
but mat2x3(i, j) triggers a compilation error,
so we have to use :
mat2x3 m = make_mat2x3(i, j);

What types of matrix constructors are supported/unsupported in MSL? If possible, I would do this only for non supported constructors. So we still can use: `mat3 m = mat3(i, j, k);` but `mat2x3(i, j)` triggers a compilation error, so we have to use : `mat2x3 m = make_mat2x3(i, j);`

Clément Foucault commented

2024-03-05 13:15:36 +01:00

The goal of prohibiting the use of the builtin constructors is to make sure it triggers an error if it not implemented on both MSL and GLSL. But it is not possible to selectively prohibit the usage of some constructors and allow some others.

MSL does support the following constructors (extended to all matrix types):

float2x2(float)
float2x2(float2,float2)
float2x2(float,float,float,float)

but does not support the following (but GLSL does):

float3x3(float2x2)
float3x3(float4x4)
float2x2(float2,float,float)

The goal of prohibiting the use of the builtin constructors is to make sure it triggers an error if it not implemented on both MSL and GLSL. But it is not possible to selectively prohibit the usage of some constructors and allow some others. MSL does support the following constructors (extended to all matrix types): ``` float2x2(float) float2x2(float2,float2) float2x2(float,float,float,float) ``` but does **not** support the following (but GLSL does): ``` float3x3(float2x2) float3x3(float4x4) float2x2(float2,float,float) ```

Clément Foucault commented

2024-03-05 13:18:44 +01:00

The fact that mat2x3(i, j) doesn't work is because it's missing implementation inside mtl_shader_defines.msl. But the current system forces us to re-implement all possible constructor for every types because of the macro/string replacement.

The fact that `mat2x3(i, j)` doesn't work is because it's missing implementation inside `mtl_shader_defines.msl`. But the current system forces us to re-implement all possible constructor for every types because of the macro/string replacement.

Miguel Pozo commented

2024-03-05 15:22:48 +01:00

Then why not add the missing constructors in mtl_shader_defines.msl?

Then why not add the missing constructors in `mtl_shader_defines.msl`?

Clément Foucault commented

2024-03-05 16:49:39 +01:00

Because all of them needs to be added explicitly. Which is both impractical, error prone, and doesn't solve the issue that this still needs string search and replace over the whole shader source, nor does it fix the fact that some invalid constructors in MSL would still be allowed in GLSL.

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GPU: Add explicit matrix constructor #119031

Proposal