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MultiTextureStyle rework : fixed error when maxTextures > 2, up to 16… #1144

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MultiTextureStyle rework : fixed error when maxTextures > 2, up to 16… #1144

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29ebaf8
MultiTextureStyle rework : fixed error when maxTextures > 2, up to 16…
MatseFR Feb 25, 2026
7b47cc9
MultiTextureStyle : fixed issue with fragment constants in baseline p…
MatseFR Mar 9, 2026
105f04c
MultiTextureStyle : maxTextures can be set before Starling is started…
MatseFR Mar 11, 2026
4badaed
MultiTextureStyle : fixed typo in doc
MatseFR Mar 11, 2026
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221 changes: 159 additions & 62 deletions starling/src/starling/styles/MultiTextureStyle.as
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,8 @@
package starling.styles
{
import flash.geom.Matrix;
import starling.core.Starling;
import starling.textures.ConcreteTexture;

import starling.display.Mesh;
import starling.rendering.MeshEffect;
Expand All @@ -19,7 +21,7 @@ package starling.styles
import starling.rendering.VertexDataFormat;
import starling.textures.Texture;

/** Provides a way to batch up to 4 different textures in one draw call, at the cost of more complex custom Fragment Shaders
/** Provides a way to batch up to 5 (baseline profiles) or 16 different textures in one draw call, at the cost of more complex custom Fragment Shaders
* To use this, set Mesh.defaultStyle to MultiTextureStyle (ideally before Starling is initialised!)
**/
public class MultiTextureStyle extends MeshStyle
Expand All @@ -28,8 +30,16 @@ package starling.styles
public static const VERTEX_FORMAT:VertexDataFormat =
MeshStyle.VERTEX_FORMAT.extend("texture:float1");

/** Maximum number of textures that can be batched. */
public static const MAX_NUM_TEXTURES:int = 5;
private static var _MAX_NUM_TEXTURES:int = 5;

/**
* Maximum number of textures that can be batched.
* Default value is 5 (which is the absolute max with baseline profile)
* until <code>MultiTextureStyle.init()</code> has been called with Starling started
* You can call it manually if you want/need, otherwise it will be called by the
* first MultiTextureStyle instance created.
*/
public static function get MAX_NUM_TEXTURES():int { return _MAX_NUM_TEXTURES; }

private var _dirty:Boolean = true;
private const _textures:Vector.<Texture> = new Vector.<Texture>();
Expand All @@ -41,11 +51,50 @@ package starling.styles
public static function get maxTextures():int { return sMaxTextures; }
public static function set maxTextures(value:int):void
{
value = value < 1 ? 1 : value;
sMaxTextures = value > MAX_NUM_TEXTURES ? MAX_NUM_TEXTURES : value;
if (!_initDone) init();

if (!_initDone)
{
// we don't know the profile yet, allow a max value of 16 (absolute max on non-baseline profile)
// that number might be reduced when we can finally check profile
value = value < 1 ? 1 : value > 16 ? 16 : value;
sMaxTextures = value;
}
else
{
value = value < 1 ? 1 : value;
sMaxTextures = value > _MAX_NUM_TEXTURES ? _MAX_NUM_TEXTURES : value;
}
}

public function MultiTextureStyle() {}

private static var _TEXTURE_INDEX_FACTOR:Number;

private static var _initDone:Boolean = false;
public static function init():void
{
if (_initDone) return;
if (Starling.current == null) return;

if (Starling.current.profile.indexOf("baseline") != -1)
{
_MAX_NUM_TEXTURES = 5;
_TEXTURE_INDEX_FACTOR = 4.0;
}
else
{
_MAX_NUM_TEXTURES = 16;
_TEXTURE_INDEX_FACTOR = 1.0;
}

if (sMaxTextures > _MAX_NUM_TEXTURES) sMaxTextures = _MAX_NUM_TEXTURES;

_initDone = true;
}

public function MultiTextureStyle()
{
if (!_initDone) init();
}

/** @private */
override public function copyFrom(meshStyle:MeshStyle):void
Expand Down Expand Up @@ -120,11 +169,14 @@ package starling.styles
numVertices:int = -1):void
{
var i:int;
var count:int;

if (matrix && _dirty)
{
for (i = 0; i < vertexData.numVertices; i++)
count = vertexData.numVertices;
for (i = 0; i < count; i++)
vertexData.setFloat(i, "texture", 0);

_dirty = false;
}

Expand All @@ -135,8 +187,8 @@ package starling.styles
if (mtTarget)
{
var dirty:Boolean = false;

for (i = 0; i < numTextures; i++)
count = numTextures;
for (i = 0; i < count; i++)
{
const texture:Texture = getTexture(i);
var textureIndexOnTarget:int = mtTarget.getTextureIndex(texture);
Expand All @@ -161,12 +213,12 @@ package starling.styles
for (i = 0; i < numVertices; i++)
{
const sourceTexID:int = Math.round(targetVertexData.getFloat(targetVertexID + i,
"texture") * 4);
"texture") * _TEXTURE_INDEX_FACTOR);
const targetTexID:int = sTextureIndexMap[sourceTexID];

if (sourceTexID != targetTexID)
targetVertexData.setFloat(targetVertexID + i, "texture",
targetTexID / 4);
targetTexID / _TEXTURE_INDEX_FACTOR);
}
}
}
Expand All @@ -188,16 +240,19 @@ package starling.styles
// in the list.
private function getTextureIndex(texture:Texture):int
{
for (var i:int = 0; i < numTextures; i++)
if (getTexture(i).root == texture.root) return i;
if (this.texture.root == texture) return 0;
const count:int = _textures.length;
for (var i:int = 0; i < count; i++)
if (_textures[i] == texture) return i + 1;

return -1;
}

// Returns an element of the shared texture list.
[Inline]
private function getTexture(index:int):Texture
{
return index > 0 ? _textures[index - 1] : texture;
return index > 0 ? _textures[index - 1] : texture.root;
}

// Returns the length of the shared texture list.
Expand Down Expand Up @@ -227,22 +282,40 @@ class MultiTextureEffect extends MeshEffect

private var _isBaseline:Boolean;

private static const kTextureIndices:Vector.<Number> = new <Number>[
private static const baselineTextureIndices:Vector.<Number> = new <Number>[
0.125, 0.375, 0.625, 0.875,
1, 0, 0, 0
];

private static const textureIndices:Vector.<Number> = new <Number>[
0.5, 1.5, 2.5, 3.5,
4.5, 5.5, 6.5, 7.5,
8.5, 9.5, 10.5, 11.5,
12.5, 13.5, 14.5, 15.5
];

private var _multiTexturingConstants:Vector.<Number>;

public function MultiTextureEffect()
{
_isBaseline = Starling.current.profile.indexOf("baseline") != -1;
if (_isBaseline)
{
_multiTexturingConstants = baselineTextureIndices;
}
else
{
_multiTexturingConstants = textureIndices;
}
}

override protected function get programVariantName():uint
{
var bits:uint = super.programVariantName;

for (var i:int = 0; i < textures.length; i++)
bits |= RenderUtil.getTextureVariantBits(textures[i]) << (4 * i + 4);
bits |= RenderUtil.getTextureVariantBits(textures[i]) << (i + 4);

return bits;
}

Expand Down Expand Up @@ -307,51 +380,12 @@ class MultiTextureEffect extends MeshEffect
}
else
{
if (length > 1)
{
fragmentShader.push(
"slt ft4, v2.xxxx, fc0",
"sub ft6, fc1.xxxx, ft4",
"min ft6.xyz, ft6.xyz, ft4.yzw",
"ifg ft4.x, fc0.z",
tex("ft5", "v0", 0, texture),
"eif",
"ifg ft6.x, fc0.z",
tex("ft5", "v0", 1, textures[0]),
"eif",
"ifg ft6.y, fc0.z",
tex("ft5", "v0", 2, textures[1]),
"eif"
);
if (length > 2)
{
fragmentShader.push(
"ifg ft6.z, fc0.z",
tex("ft5", "v0", 3, textures[2]),
"eif"
);
if (length > 3)
{
fragmentShader.push(
"ifg ft6.w, fc0.z",
tex("ft5", "v0", 4, textures[3]),
"eif"
);
}
}
}
else
{
fragmentShader.push(
"ifl v2.x, fc0.x",
tex("ft5", "v0", 0, texture),
"els",
tex("ft5", "v0", 1, textures[0]),
"eif"
);
}
textures.unshift(texture); // add base texture temporarily
multiTex(fragmentShader, textures);
textures.shift(); // remove base texture

fragmentShader.push(
"mul oc, ft5, v1" // multiply color with texel color
"mul oc, ft0, v1" // multiply color with texel color
);
}
return Program.fromSource(vertexShader, fragmentShader.join("\n"),
Expand All @@ -360,6 +394,69 @@ class MultiTextureEffect extends MeshEffect

return super.createProgram();
}

protected function multiTex(data:Vector.<String>, textures:Vector.<Texture>, numTextures:int = 0, textureOffset:int = 0, textureRegister:String = "ft0", textureIndexSource:String = "v2.x", constantsStartIndex:int = 0):void
{
if (numTextures == 0) numTextures = textures.length;

if (numTextures <= 2)
{
if (numTextures == 2)
{
checkTexIndex(data, textureOffset, textureIndexSource, constantsStartIndex);
data[data.length] = RenderUtil.createAGALTexOperation(textureRegister, "v0", textureOffset, textures[textureOffset]);
data[data.length] = "els";
data[data.length] = RenderUtil.createAGALTexOperation(textureRegister, "v0", textureOffset + 1, textures[textureOffset + 1]);
data[data.length] = "eif";
}
else
{
data[data.length] = RenderUtil.createAGALTexOperation(textureRegister, "v0", textureOffset, textures[textureOffset]);
}
}
else
{
var halfNumTextures:int = Math.ceil(numTextures / 2);
var remainingTextures:int = numTextures - halfNumTextures;

checkTexIndex(data, textureOffset + halfNumTextures - 1, textureIndexSource, constantsStartIndex);
multiTex(data, textures, halfNumTextures, textureOffset, textureRegister, textureIndexSource, constantsStartIndex);
data[data.length] = "els";
multiTex(data, textures, remainingTextures, textureOffset + halfNumTextures, textureRegister, textureIndexSource, constantsStartIndex);
data[data.length] = "eif";
}
}

protected function checkTexIndex(data:Vector.<String>, textureNum:int, textureIndexSource:String, constantsStartIndex:int):void
{
var constantIndex:int = constantsStartIndex + Math.floor(textureNum / 4);
var constantSubIndex:int = textureNum % 4;
var constant:String;

switch (constantSubIndex)
{
case 0 :
constant = " fc" + constantIndex + ".x";
break;

case 1 :
constant = " fc" + constantIndex + ".y";
break;

case 2 :
constant = " fc" + constantIndex + ".z";
break;

case 3 :
constant = " fc" + constantIndex + ".w";
break;

default :
throw new Error("incorrect constant sub index");
}

data[data.length] = "ifl " + textureIndexSource + constant;
}

override protected function beforeDraw(context:Context3D):void
{
Expand All @@ -379,7 +476,7 @@ class MultiTextureEffect extends MeshEffect
}
vertexFormat.setVertexBufferAt(3, vertexBuffer, "texture");
context.setProgramConstantsFromVector(Context3DProgramType.FRAGMENT,
0, kTextureIndices, length > 1 || _isBaseline ? -1 : 1);
0, _multiTexturingConstants, _isBaseline ? -1 : Math.ceil((length + 1) / 4));
}
}

Expand Down
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