ebiten/internal/graphics/vertex.go
Pierre Curto 4de807cc44
all: fix typos (#2558)
Signed-off-by: Pierre Curto <pierre.curto@gmail.com>
2023-01-28 19:06:38 +09:00

137 lines
4.0 KiB
Go

// 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
}
}