ebiten/internal/graphics/vertices.go
2019-02-16 14:50:03 +09:00

169 lines
3.7 KiB
Go

// Copyright 2017 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package graphics
import (
"fmt"
"sync"
)
var (
theVerticesBackend = &verticesBackend{}
)
type verticesBackend struct {
backend []float32
head int
m sync.Mutex
}
const (
IndicesNum = (1 << 16) / 3 * 3 // Adjust num for triangles.
VertexFloatNum = 12
)
func (v *verticesBackend) slice(n int) []float32 {
const num = 1024
if n > num {
panic(fmt.Sprintf("graphics: n must be <= num but not: n: %d, num: %d", n, num))
}
v.m.Lock()
need := n * VertexFloatNum
if v.head+need > len(v.backend) {
v.backend = nil
v.head = 0
}
if v.backend == nil {
v.backend = make([]float32, VertexFloatNum*num)
}
s := v.backend[v.head : v.head+need]
v.head += need
v.m.Unlock()
return s
}
func QuadVertices(width, height int, sx0, sy0, sx1, sy1 int, a, b, c, d, tx, ty float32, cr, cg, cb, ca float32) []float32 {
// width and height are the source image's size.
// For performance reason, graphics.InternalImageSize is not applied to width/height here.
if !isInternalImageSize(width) {
panic(fmt.Sprintf("graphics: width must be an internal image size at QuadVertices: %d", width))
}
if !isInternalImageSize(height) {
panic(fmt.Sprintf("graphics: height must be an internal image size at QuadVertices: %d", height))
}
if sx0 >= sx1 || sy0 >= sy1 {
return nil
}
if sx1 <= 0 || sy1 <= 0 {
return nil
}
wf := float32(width)
hf := float32(height)
u0, v0, u1, v1 := float32(sx0)/wf, float32(sy0)/hf, float32(sx1)/wf, float32(sy1)/hf
return quadVerticesImpl(wf, hf, float32(sx1-sx0), float32(sy1-sy0), u0, v0, u1, v1, a, b, c, d, tx, ty, cr, cg, cb, ca)
}
const TexelAdjustmentFactor = 512.0
func quadVerticesImpl(sw, sh, x, y, u0, v0, u1, v1, a, b, c, d, tx, ty, cr, cg, cb, ca float32) []float32 {
// Specifying a range explicitly here is redundant but this helps optimization
// to eliminate boundary checks.
//
// 4*VertexFloatNum is better than 48, but in GopherJS, optimization might not work.
vs := theVerticesBackend.slice(4)[0:48]
ax, by, cx, dy := a*x, b*y, c*x, d*y
du := 1.0 / sw / TexelAdjustmentFactor
dv := 1.0 / sh / TexelAdjustmentFactor
// Vertex coordinates
vs[0] = tx
vs[1] = ty
// Texture coordinates: first 2 values indicates the actual coodinate, and
// the second indicates diagonally opposite coodinates.
// The second is needed to calculate source rectangle size in shader programs.
vs[2] = u0
vs[3] = v0
vs[4] = u0
vs[5] = v0
vs[6] = u1 - du
vs[7] = v1 - dv
vs[8] = cr
vs[9] = cg
vs[10] = cb
vs[11] = ca
// and the same for the other three coordinates
vs[12] = ax + tx
vs[13] = cx + ty
vs[14] = u1
vs[15] = v0
vs[16] = u0
vs[17] = v0
vs[18] = u1 - du
vs[19] = v1 - dv
vs[20] = cr
vs[21] = cg
vs[22] = cb
vs[23] = ca
vs[24] = by + tx
vs[25] = dy + ty
vs[26] = u0
vs[27] = v1
vs[28] = u0
vs[29] = v0
vs[30] = u1 - du
vs[31] = v1 - dv
vs[32] = cr
vs[33] = cg
vs[34] = cb
vs[35] = ca
vs[36] = ax + by + tx
vs[37] = cx + dy + ty
vs[38] = u1
vs[39] = v1
vs[40] = u0
vs[41] = v0
vs[42] = u1 - du
vs[43] = v1 - dv
vs[44] = cr
vs[45] = cg
vs[46] = cb
vs[47] = ca
return vs
}
var (
quadIndices = []uint16{0, 1, 2, 1, 2, 3}
)
func QuadIndices() []uint16 {
return quadIndices
}