mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-11-10 13:07:26 +01:00
104 lines
2.7 KiB
Go
104 lines
2.7 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 boundaryInBytes = 16
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func calculateMemoryOffsets(uniforms []shaderir.Type) []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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var offsets []int
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var head int
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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)/boundaryInBytes + 1) * boundaryInBytes
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}
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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 uniforms {
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switch u.Main {
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case shaderir.Float:
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offsets = append(offsets, head)
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head += 4
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case shaderir.Vec2:
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if head%boundaryInBytes >= 4*3 {
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head = align(head)
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}
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offsets = append(offsets, head)
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head += 4 * 2
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case shaderir.Vec3:
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if head%boundaryInBytes >= 4*2 {
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head = align(head)
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}
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offsets = append(offsets, head)
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head += 4 * 3
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case shaderir.Vec4:
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if head%boundaryInBytes >= 4*1 {
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head = align(head)
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}
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offsets = append(offsets, head)
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head += 4 * 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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head = align(head)
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offsets = append(offsets, head)
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head += 4 * 6
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case shaderir.Mat3:
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head = align(head)
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offsets = append(offsets, head)
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head += 4 * 11
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case shaderir.Mat4:
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head = align(head)
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offsets = append(offsets, head)
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head += 4 * 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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head = align(head)
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offsets = append(offsets, head)
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n := u.Sub[0].FloatNum()
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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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head += (u.Length - 1) * align(4*n)
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// The last element is not with a padding.
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head += 4 * 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: %d", u.Main))
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}
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}
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return offsets
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}
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