mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-09-20 05:12:18 +02:00
142 lines
3.1 KiB
Go
142 lines
3.1 KiB
Go
// Copyright 2019 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 graphics
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import (
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"github.com/hajimehoshi/ebiten/internal/web"
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)
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const (
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ShaderImageNum = 4
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// PreservedUniformVariablesNum represents the number of preserved uniform variables.
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// Any shaders in Ebiten must have these uniform variables.
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//
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// All the preversed uniform variables are vec2 so far.
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PreservedUniformVariablesNum = 1 + // the destination texture size
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ShaderImageNum + // the texture sizes
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(ShaderImageNum - 1) // the offsets of the second and the following images
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)
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func TextureOffsetUniformVariableIndex(i int) int {
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if i == 0 {
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panic("graphics: the texture 0 doesn't have its offset")
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}
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return 1 + ShaderImageNum + i - 1
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}
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const (
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IndicesNum = (1 << 16) / 3 * 3 // Adjust num for triangles.
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VertexFloatNum = 8
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)
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var (
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quadIndices = []uint16{0, 1, 2, 1, 2, 3}
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)
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func QuadIndices() []uint16 {
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return quadIndices
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}
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var (
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theVerticesBackend = &verticesBackend{
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backend: make([]float32, VertexFloatNum*1024),
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}
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)
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type verticesBackend struct {
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backend []float32
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head int
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}
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func (v *verticesBackend) slice(n int, last bool) []float32 {
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// As this is called only from GopherJS, mutex is not required.
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need := n * VertexFloatNum
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if l := len(v.backend); v.head+need > l {
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for v.head+need > l {
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l *= 2
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}
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v.backend = make([]float32, l)
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v.head = 0
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}
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s := v.backend[v.head : v.head+need]
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if last {
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// If last is true, the vertices backend is sent to GPU and it is fine to reuse the slice.
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v.head = 0
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} else {
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v.head += need
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}
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return s
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}
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func vertexSlice(n int, last bool) []float32 {
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if web.IsGopherJS() {
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// In GopherJS, allocating memory by make is expensive. Use the backend instead.
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return theVerticesBackend.slice(n, last)
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}
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return make([]float32, n*VertexFloatNum)
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}
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func QuadVertices(sx0, sy0, sx1, sy1 float32, a, b, c, d, tx, ty float32, cr, cg, cb, ca float32, last bool) []float32 {
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x := sx1 - sx0
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y := sy1 - sy0
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ax, by, cx, dy := a*x, b*y, c*x, d*y
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u0, v0, u1, v1 := float32(sx0), float32(sy0), float32(sx1), float32(sy1)
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// This function is very performance-sensitive and implement in a very dumb way.
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vs := vertexSlice(4, last)
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_ = vs[:32]
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vs[0] = tx
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vs[1] = ty
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vs[2] = u0
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vs[3] = v0
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vs[4] = cr
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vs[5] = cg
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vs[6] = cb
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vs[7] = ca
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vs[8] = ax + tx
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vs[9] = cx + ty
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vs[10] = u1
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vs[11] = v0
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vs[12] = cr
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vs[13] = cg
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vs[14] = cb
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vs[15] = ca
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vs[16] = by + tx
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vs[17] = dy + ty
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vs[18] = u0
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vs[19] = v1
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vs[20] = cr
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vs[21] = cg
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vs[22] = cb
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vs[23] = ca
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vs[24] = ax + by + tx
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vs[25] = cx + dy + ty
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vs[26] = u1
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vs[27] = v1
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vs[28] = cr
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vs[29] = cg
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vs[30] = cb
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vs[31] = ca
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return vs
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}
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