-
-
Notifications
You must be signed in to change notification settings - Fork 635
/
vertex.go
136 lines (121 loc) · 3.99 KB
/
vertex.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
// Copyright 2019 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
const (
ShaderImageCount = 4
// PreservedUniformVariablesCount represents the number of preserved uniform variables.
// Any shaders in Ebitengine must have these uniform variables.
PreservedUniformVariablesCount = 1 + // the destination texture size
1 + // the texture sizes array
1 + // the texture destination region's origin
1 + // the texture destination region's size
1 + // the offsets array of the second and the following images
1 + // the texture source region's origin
1 + // the texture source region's size
1 // the projection matrix
TextureDestinationSizeUniformVariableIndex = 0
TextureSourceSizesUniformVariableIndex = 1
TextureDestinationRegionOriginUniformVariableIndex = 2
TextureDestinationRegionSizeUniformVariableIndex = 3
TextureSourceOffsetsUniformVariableIndex = 4
TextureSourceRegionOriginUniformVariableIndex = 5
TextureSourceRegionSizeUniformVariableIndex = 6
ProjectionMatrixUniformVariableIndex = 7
PreservedUniformUint32Count = 2 + // the destination texture size
2*ShaderImageCount + // the texture sizes array
2 + // the texture destination region's origin
2 + // the texture destination region's size
2*(ShaderImageCount-1) + // the offsets array of the second and the following images
2 + // the texture source region's origin
2 + // the texture source region's size
16 // the projection matrix
)
const (
IndicesCount = (1 << 16) / 3 * 3 // Adjust num for triangles.
VertexFloatCount = 8
)
var (
quadIndices = []uint16{0, 1, 2, 1, 2, 3}
)
func QuadIndices() []uint16 {
return quadIndices
}
// QuadVertices sets a float32 slice for a quadrangle.
// QuadVertices sets a slice that never overlaps with other slices returned this function,
// and users can do optimization based on this fact.
func QuadVertices(dst []float32, sx0, sy0, sx1, sy1 float32, a, b, c, d, tx, ty float32, cr, cg, cb, ca float32) {
x := sx1 - sx0
y := sy1 - sy0
ax, by, cx, dy := a*x, b*y, c*x, d*y
u0, v0, u1, v1 := sx0, sy0, sx1, sy1
// This function is very performance-sensitive and implement in a very dumb way.
_ = dst[:4*VertexFloatCount]
dst[0] = adjustDestinationPixel(tx)
dst[1] = adjustDestinationPixel(ty)
dst[2] = u0
dst[3] = v0
dst[4] = cr
dst[5] = cg
dst[6] = cb
dst[7] = ca
dst[8] = adjustDestinationPixel(ax + tx)
dst[9] = adjustDestinationPixel(cx + ty)
dst[10] = u1
dst[11] = v0
dst[12] = cr
dst[13] = cg
dst[14] = cb
dst[15] = ca
dst[16] = adjustDestinationPixel(by + tx)
dst[17] = adjustDestinationPixel(dy + ty)
dst[18] = u0
dst[19] = v1
dst[20] = cr
dst[21] = cg
dst[22] = cb
dst[23] = ca
dst[24] = adjustDestinationPixel(ax + by + tx)
dst[25] = adjustDestinationPixel(cx + dy + ty)
dst[26] = u1
dst[27] = v1
dst[28] = cr
dst[29] = cg
dst[30] = cb
dst[31] = ca
}
func adjustDestinationPixel(x float32) float32 {
// Avoid the center of the pixel, which is problematic (#929, #1171).
// Instead, align the vertices with about 1/3 pixels.
//
// The intention here is roughly this code:
//
// float32(math.Floor((float64(x)+1.0/6.0)*3) / 3)
//
// The actual implementation is more optimized than the above implementation.
ix := float32(int(x))
if x < 0 && x != ix {
ix -= 1
}
frac := x - ix
switch {
case frac < 3.0/16.0:
return ix
case frac < 8.0/16.0:
return ix + 5.0/16.0
case frac < 13.0/16.0:
return ix + 11.0/16.0
default:
return ix + 16.0/16.0
}
}