mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2025-01-03 15:48:53 +01:00
108 lines
3.5 KiB
Go
108 lines
3.5 KiB
Go
// Copyright 2022 The Ebiten Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package hlsl
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import (
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"fmt"
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"github.com/hajimehoshi/ebiten/v2/internal/shaderir"
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)
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const UniformVariableBoundaryInDwords = 4
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// UniformVariableOffsetsInDwords returns the offsets of the uniform variables in DWROD units in the HLSL layout.
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func UniformVariableOffsetsInDwords(program *shaderir.Program) []int {
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// https://docs.microsoft.com/en-us/windows/win32/direct3dhlsl/dx-graphics-hlsl-packing-rules
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// https://github.com/microsoft/DirectXShaderCompiler/wiki/Buffer-Packing
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align := func(x int) int {
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if x == 0 {
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return 0
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}
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return ((x-1)/UniformVariableBoundaryInDwords + 1) * UniformVariableBoundaryInDwords
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}
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var offsetsInDwords []int
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var headInDwords int
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// TODO: Reorder the variables with packoffset.
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// See https://docs.microsoft.com/en-us/windows/win32/direct3dhlsl/dx-graphics-hlsl-variable-packoffset
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for _, u := range program.Uniforms {
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switch u.Main {
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case shaderir.Float:
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offsetsInDwords = append(offsetsInDwords, headInDwords)
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headInDwords += 1
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case shaderir.Int:
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offsetsInDwords = append(offsetsInDwords, headInDwords)
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headInDwords += 1
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case shaderir.Vec2, shaderir.IVec2:
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if headInDwords%UniformVariableBoundaryInDwords >= 3 {
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headInDwords = align(headInDwords)
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}
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offsetsInDwords = append(offsetsInDwords, headInDwords)
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headInDwords += 2
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case shaderir.Vec3, shaderir.IVec3:
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if headInDwords%UniformVariableBoundaryInDwords >= 2 {
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headInDwords = align(headInDwords)
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}
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offsetsInDwords = append(offsetsInDwords, headInDwords)
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headInDwords += 3
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case shaderir.Vec4, shaderir.IVec4:
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if headInDwords%UniformVariableBoundaryInDwords >= 1 {
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headInDwords = align(headInDwords)
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}
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offsetsInDwords = append(offsetsInDwords, headInDwords)
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headInDwords += 4
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case shaderir.Mat2:
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// For matrices, each column is aligned to the boundary.
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headInDwords = align(headInDwords)
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offsetsInDwords = append(offsetsInDwords, headInDwords)
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headInDwords += 6
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case shaderir.Mat3:
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headInDwords = align(headInDwords)
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offsetsInDwords = append(offsetsInDwords, headInDwords)
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headInDwords += 11
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case shaderir.Mat4:
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headInDwords = align(headInDwords)
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offsetsInDwords = append(offsetsInDwords, headInDwords)
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headInDwords += 16
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case shaderir.Array:
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// Each array is 16-byte aligned.
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// TODO: What if the array has 2 or more dimensions?
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headInDwords = align(headInDwords)
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offsetsInDwords = append(offsetsInDwords, headInDwords)
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n := u.Sub[0].DwordCount()
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switch u.Sub[0].Main {
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case shaderir.Mat2:
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n = 6
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case shaderir.Mat3:
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n = 11
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case shaderir.Mat4:
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n = 16
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}
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headInDwords += (u.Length - 1) * align(n)
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// The last element is not with a padding.
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headInDwords += n
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case shaderir.Struct:
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// TODO: Implement this
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panic("hlsl: offset for a struct is not implemented yet")
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default:
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panic(fmt.Sprintf("hlsl: unexpected type: %s", u.String()))
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}
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}
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return offsetsInDwords
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}
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