ebiten/internal/graphics/vertex.go
2024-08-25 18:11:39 +09:00

174 lines
5.0 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 (
ShaderSrcImageCount = 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 source texture sizes array
1 + // the destination image region origin
1 + // the destination image region size
1 + // the source image region origins
1 + // the source image region sizes array
1 // the projection matrix
ProjectionMatrixUniformVariableIndex = 6
PreservedUniformUint32Count = 2 + // the destination texture size
2*ShaderSrcImageCount + // the source texture sizes array
2 + // the destination image region origin
2 + // the destination image region size
2*ShaderSrcImageCount + // the source image region origins array
2*ShaderSrcImageCount + // the source image region sizes array
16 // the projection matrix
)
const (
VertexFloatCount = 12
)
var (
quadIndices = []uint32{0, 1, 2, 1, 2, 3}
)
func QuadIndices() []uint32 {
return quadIndices
}
// QuadVerticesFromSrcAndMatrix sets a float32 slice for a quadrangle.
func QuadVerticesFromSrcAndMatrix(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.
// Remove the boundary check.
dst = 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[VertexFloatCount] = adjustDestinationPixel(ax + tx)
dst[VertexFloatCount+1] = adjustDestinationPixel(cx + ty)
dst[VertexFloatCount+2] = u1
dst[VertexFloatCount+3] = v0
dst[VertexFloatCount+4] = cr
dst[VertexFloatCount+5] = cg
dst[VertexFloatCount+6] = cb
dst[VertexFloatCount+7] = ca
dst[2*VertexFloatCount] = adjustDestinationPixel(by + tx)
dst[2*VertexFloatCount+1] = adjustDestinationPixel(dy + ty)
dst[2*VertexFloatCount+2] = u0
dst[2*VertexFloatCount+3] = v1
dst[2*VertexFloatCount+4] = cr
dst[2*VertexFloatCount+5] = cg
dst[2*VertexFloatCount+6] = cb
dst[2*VertexFloatCount+7] = ca
dst[3*VertexFloatCount] = adjustDestinationPixel(ax + by + tx)
dst[3*VertexFloatCount+1] = adjustDestinationPixel(cx + dy + ty)
dst[3*VertexFloatCount+2] = u1
dst[3*VertexFloatCount+3] = v1
dst[3*VertexFloatCount+4] = cr
dst[3*VertexFloatCount+5] = cg
dst[3*VertexFloatCount+6] = cb
dst[3*VertexFloatCount+7] = ca
}
// QuadVerticesFromDstAndSrc sets a float32 slice for a quadrangle.
func QuadVerticesFromDstAndSrc(dst []float32, dx0, dy0, dx1, dy1, sx0, sy0, sx1, sy1, cr, cg, cb, ca float32) {
dx0 = adjustDestinationPixel(dx0)
dy0 = adjustDestinationPixel(dy0)
dx1 = adjustDestinationPixel(dx1)
dy1 = adjustDestinationPixel(dy1)
// Remove the boundary check.
dst = dst[:4*VertexFloatCount]
dst[0] = dx0
dst[1] = dy0
dst[2] = sx0
dst[3] = sy0
dst[4] = cr
dst[5] = cg
dst[6] = cb
dst[7] = ca
dst[VertexFloatCount] = dx1
dst[VertexFloatCount+1] = dy0
dst[VertexFloatCount+2] = sx1
dst[VertexFloatCount+3] = sy0
dst[VertexFloatCount+4] = cr
dst[VertexFloatCount+5] = cg
dst[VertexFloatCount+6] = cb
dst[VertexFloatCount+7] = ca
dst[2*VertexFloatCount] = dx0
dst[2*VertexFloatCount+1] = dy1
dst[2*VertexFloatCount+2] = sx0
dst[2*VertexFloatCount+3] = sy1
dst[2*VertexFloatCount+4] = cr
dst[2*VertexFloatCount+5] = cg
dst[2*VertexFloatCount+6] = cb
dst[2*VertexFloatCount+7] = ca
dst[3*VertexFloatCount] = dx1
dst[3*VertexFloatCount+1] = dy1
dst[3*VertexFloatCount+2] = sx1
dst[3*VertexFloatCount+3] = sy1
dst[3*VertexFloatCount+4] = cr
dst[3*VertexFloatCount+5] = cg
dst[3*VertexFloatCount+6] = cb
dst[3*VertexFloatCount+7] = 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
}
}