internal/graphicscommand: use buffers for []float32 to reduce allocations

internal/graphicscommand/command.go

@@ -71,11 +71,8 @@ type commandQueue struct {
 
 	drawTrianglesCommandPool drawTrianglesCommandPool
 
-	// float32sBuffer is a reusable buffer to allocate []float32.
-	// float32sBuffer's index is switched at the end of the frame,
-	//  and the buffer of the original index is kept until the next frame ends.
-	float32sBuffer      [2][]float32
-	float32sBufferIndex int
+	float32sBuffer      buffer[float32]
+	float32SlicesBuffer buffer[[]float32]
 }
 
 // theCommandQueue is the command queue for the current process.
@@ -172,9 +169,8 @@ func (q *commandQueue) Flush(graphicsDriver graphicsdriver.Graphics, endFrame bo
 		err = q.flush(graphicsDriver, endFrame)
 	})
 	if endFrame {
-		q.float32sBuffer[q.float32sBufferIndex] = q.float32sBuffer[q.float32sBufferIndex][:0]
-		q.float32sBufferIndex++
-		q.float32sBufferIndex %= len(q.float32sBuffer)
+		q.float32sBuffer.reset()
+		q.float32SlicesBuffer.reset()
 	}
 	return
 }
@@ -590,29 +586,20 @@ func roundUpPower2(x int) int {
 	return p2
 }
 
-func (q *commandQueue) allocFloat32s(n int) []float32 {
-	buf := q.float32sBuffer[q.float32sBufferIndex]
-	if len(buf)+n > cap(buf) {
-		buf = make([]float32, 0, max(roundUpPower2(len(buf)+n), 16))
-	}
-	s := buf[len(buf) : len(buf)+n]
-	q.float32sBuffer[q.float32sBufferIndex] = buf[:len(buf)+n]
-	return s
-}
-
 func (q *commandQueue) prependPreservedUniforms(uniforms [][]float32, dst *Image, srcs [graphics.ShaderImageCount]*Image, offsets [graphics.ShaderImageCount - 1][2]float32, dstRegion, srcRegion graphicsdriver.Region) [][]float32 {
-	uniforms = append(uniforms, make([][]float32, graphics.PreservedUniformVariablesCount)...)
-	copy(uniforms[graphics.PreservedUniformVariablesCount:], uniforms)
+	origUniforms := uniforms
+	uniforms = q.float32SlicesBuffer.alloc(len(origUniforms) + graphics.PreservedUniformVariablesCount)
+	copy(uniforms[graphics.PreservedUniformVariablesCount:], origUniforms)
 
 	// Set the destination texture size.
 	dw, dh := dst.InternalSize()
-	udstsize := q.allocFloat32s(2)
+	udstsize := q.float32sBuffer.alloc(2)
 	udstsize[0] = float32(dw)
 	udstsize[1] = float32(dh)
 	uniforms[graphics.TextureDestinationSizeUniformVariableIndex] = udstsize
 
 	// Set the source texture sizes.
-	usizes := q.allocFloat32s(2 * len(srcs))
+	usizes := q.float32sBuffer.alloc(2 * len(srcs))
 	for i, src := range srcs {
 		if src != nil {
 			w, h := src.InternalSize()
@@ -623,12 +610,12 @@ func (q *commandQueue) prependPreservedUniforms(uniforms [][]float32, dst *Image
 	uniforms[graphics.TextureSourceSizesUniformVariableIndex] = usizes
 
 	// Set the destination region.
-	udstrorig := q.allocFloat32s(2)
+	udstrorig := q.float32sBuffer.alloc(2)
 	udstrorig[0] = float32(dstRegion.X) / float32(dw)
 	udstrorig[1] = float32(dstRegion.Y) / float32(dh)
 	uniforms[graphics.TextureDestinationRegionOriginUniformVariableIndex] = udstrorig
 
-	udstrsize := q.allocFloat32s(2)
+	udstrsize := q.float32sBuffer.alloc(2)
 	udstrsize[0] = float32(dstRegion.Width) / float32(dw)
 	udstrsize[1] = float32(dstRegion.Height) / float32(dh)
 	uniforms[graphics.TextureDestinationRegionSizeUniformVariableIndex] = udstrsize
@@ -646,7 +633,7 @@ func (q *commandQueue) prependPreservedUniforms(uniforms [][]float32, dst *Image
 	}
 
 	// Set the source offsets.
-	uoffsets := q.allocFloat32s(2 * len(offsets))
+	uoffsets := q.float32sBuffer.alloc(2 * len(offsets))
 	for i, offset := range offsets {
 		uoffsets[2*i] = offset[0]
 		uoffsets[2*i+1] = offset[1]
@@ -654,17 +641,17 @@ func (q *commandQueue) prependPreservedUniforms(uniforms [][]float32, dst *Image
 	uniforms[graphics.TextureSourceOffsetsUniformVariableIndex] = uoffsets
 
 	// Set the source region of texture0.
-	usrcrorig := q.allocFloat32s(2)
+	usrcrorig := q.float32sBuffer.alloc(2)
 	usrcrorig[0] = float32(srcRegion.X)
 	usrcrorig[1] = float32(srcRegion.Y)
 	uniforms[graphics.TextureSourceRegionOriginUniformVariableIndex] = usrcrorig
 
-	usrcrsize := q.allocFloat32s(2)
+	usrcrsize := q.float32sBuffer.alloc(2)
 	usrcrsize[0] = float32(srcRegion.Width)
 	usrcrsize[1] = float32(srcRegion.Height)
 	uniforms[graphics.TextureSourceRegionSizeUniformVariableIndex] = usrcrsize
 
-	umatrix := q.allocFloat32s(16)
+	umatrix := q.float32sBuffer.alloc(16)
 	umatrix[0] = 2 / float32(dw)
 	umatrix[1] = 0
 	umatrix[2] = 0
@@ -685,3 +672,28 @@ func (q *commandQueue) prependPreservedUniforms(uniforms [][]float32, dst *Image
 
 	return uniforms
 }
+
+// buffer is a reusable buffer to allocate []T.
+type buffer[T any] struct {
+	buf [2][]T
+
+	// index is switched at the end of the frame,
+	// and the buffer of the original index is kept until the next frame ends.
+	index int
+}
+
+func (b *buffer[T]) alloc(n int) []T {
+	buf := b.buf[b.index]
+	if len(buf)+n > cap(buf) {
+		buf = make([]T, 0, max(roundUpPower2(len(buf)+n), 16))
+	}
+	s := buf[len(buf) : len(buf)+n]
+	b.buf[b.index] = buf[:len(buf)+n]
+	return s
+}
+
+func (b *buffer[T]) reset() {
+	b.buf[b.index] = b.buf[b.index][:0]
+	b.index++
+	b.index %= len(b.buf)
+}

internal/ui/shader.go

@@ -18,7 +18,6 @@ import (
 	"fmt"
 	"strings"
 
-	"github.com/hajimehoshi/ebiten/v2/internal/graphics"
 	"github.com/hajimehoshi/ebiten/v2/internal/mipmap"
 	"github.com/hajimehoshi/ebiten/v2/internal/shaderir"
 )
@@ -73,8 +72,7 @@ func (s *Shader) ConvertUniforms(uniforms map[string]any) [][]float32 {
 		}
 	}
 
-	// Allocate a new slice with an extra capacity. This slice's length is extended at internal/graphicscommand.
-	us := make([][]float32, len(s.uniformNameToIndex), len(s.uniformNameToIndex)+graphics.PreservedUniformVariablesCount)
+	us := make([][]float32, len(s.uniformNameToIndex))
 	for name, idx := range s.uniformNameToIndex {
 		if v, ok := nameToF32s[name]; ok {
 			us[idx] = v