mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-11-10 04:57:26 +01:00
133 lines
2.7 KiB
Go
133 lines
2.7 KiB
Go
// Copyright 2017 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 ebiten
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import (
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"github.com/hajimehoshi/ebiten/internal/affine"
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"github.com/hajimehoshi/ebiten/internal/restorable"
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)
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var (
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quadFloat32Num = restorable.QuadVertexSizeInBytes() / 4
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theVerticesBackend = &verticesBackend{}
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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) get() []float32 {
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const num = 256
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if v.backend == nil {
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v.backend = make([]float32, quadFloat32Num*num)
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}
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s := v.backend[v.head : v.head+quadFloat32Num]
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v.head += quadFloat32Num
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if v.head+quadFloat32Num > len(v.backend) {
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v.backend = nil
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v.head = 0
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}
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return s
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}
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func vertices(sx0, sy0, sx1, sy1 int, width, height int, geo *affine.GeoM) []float32 {
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if sx0 == sx1 || sy0 == sy1 {
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return nil
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}
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// TODO: This function should be in graphics package?
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vs := theVerticesBackend.get()
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a, b, c, d, tx, ty := geo.Elements()
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g0 := float32(a)
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g1 := float32(b)
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g2 := float32(c)
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g3 := float32(d)
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g4 := float32(tx)
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g5 := float32(ty)
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w := 1
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h := 1
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for w < width {
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w *= 2
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}
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for h < height {
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h *= 2
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}
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wf := float32(w)
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hf := float32(h)
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x0, y0, x1, y1 := float32(0), float32(0), float32(sx1-sx0), float32(sy1-sy0)
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u0, v0, u1, v1 := float32(sx0)/wf, float32(sy0)/hf, float32(sx1)/wf, float32(sy1)/hf
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// Vertex coordinates
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vs[0] = x0
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vs[1] = y0
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// Texture coordinates: first 2 values indicates the actual coodinate, and
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// the second indicates diagonally opposite coodinates.
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// The second is needed to calculate source rectangle size in shader programs.
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vs[2] = u0
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vs[3] = v0
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vs[4] = u1
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vs[5] = v1
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// Geometry matrix
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vs[6] = g0
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vs[7] = g1
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vs[8] = g2
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vs[9] = g3
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vs[10] = g4
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vs[11] = g5
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vs[12] = x1
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vs[13] = y0
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vs[14] = u1
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vs[15] = v0
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vs[16] = u0
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vs[17] = v1
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vs[18] = g0
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vs[19] = g1
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vs[20] = g2
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vs[21] = g3
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vs[22] = g4
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vs[23] = g5
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vs[24] = x0
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vs[25] = y1
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vs[26] = u0
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vs[27] = v1
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vs[28] = u1
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vs[29] = v0
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vs[30] = g0
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vs[31] = g1
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vs[32] = g2
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vs[33] = g3
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vs[34] = g4
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vs[35] = g5
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vs[36] = x1
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vs[37] = y1
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vs[38] = u1
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vs[39] = v1
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vs[40] = u0
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vs[41] = v0
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vs[42] = g0
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vs[43] = g1
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vs[44] = g2
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vs[45] = g3
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vs[46] = g4
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vs[47] = g5
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return vs
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}
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