Skip to content

Optimize pen line drawing using instanced rendering #11

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 7 commits into from
Aug 16, 2024
Merged

Optimize pen line drawing using instanced rendering #11

Changes from all commits
Commits
Show all changes
7 commits
Select commit Hold shift + click to select a range
f6f1f1c
Instance rendering!
Tacodiva Aug 15, 2024
8f81761
Add fallback to "ANGLE_instanced_arrays"
Tacodiva Aug 15, 2024
3f1e425
Lint
Tacodiva Aug 15, 2024
38c4213
code style, clean up some very old stuff, fallback to non-instanced f…
GarboMuffin Aug 15, 2024
f8d0132
fix some mistakes I caused
GarboMuffin Aug 15, 2024
d6052fd
simplify part that is always the same
GarboMuffin Aug 16, 2024
368cd4d
Switch to TRIANGLE_STRIP
Tacodiva Aug 16, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
287 changes: 147 additions & 140 deletions src/PenSkin.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -24,14 +24,9 @@ const DefaultPenAttributes = {
diameter: 1
};

/**
* Reused memory location for storing a premultiplied pen color.
* @type {FloatArray}
*/
const __premultipliedColor = [0, 0, 0, 0];

const PEN_BUFFER_SIZE_LARGER = 65520;
const PEN_BUFFER_SIZE_SMALLER = 32760;
const PEN_ATTRIBUTE_BUFFER_SIZE = 163800;
const PEN_ATTRIBUTE_STRIDE = 10;
const PEN_ATTRIBUTE_STRIDE_BYTES = PEN_ATTRIBUTE_STRIDE * 4;

class PenSkin extends Skin {
/**
Expand Down Expand Up @@ -71,67 +66,90 @@ class PenSkin extends Skin {
exit: () => this._exitUsePenBuffer()
};

/** @type {WebGLRenderingContext} */
const gl = this._renderer.gl;

// tw: renderQuality attribute
this.renderQuality = 1;

// tw: keep track of native size
this._nativeSize = renderer.getNativeSize();

// tw: create the extra data structures needed to buffer pen
this._resetAttributeIndexes();
this.a_lineColor = new Float32Array(PEN_BUFFER_SIZE_LARGER);
this.a_lineThicknessAndLength = new Float32Array(PEN_BUFFER_SIZE_SMALLER);
this.a_penPoints = new Float32Array(PEN_BUFFER_SIZE_LARGER);
this.a_position = new Float32Array(PEN_BUFFER_SIZE_SMALLER);
for (let i = 0; i < this.a_position.length; i += 12) {
this.a_position[i + 0] = 1;
this.a_position[i + 1] = 0;
this.a_position[i + 2] = 0;
this.a_position[i + 3] = 0;
this.a_position[i + 4] = 1;
this.a_position[i + 5] = 1;
this.a_position[i + 6] = 1;
this.a_position[i + 7] = 1;
this.a_position[i + 8] = 0;
this.a_position[i + 9] = 0;
this.a_position[i + 10] = 0;
this.a_position[i + 11] = 1;
}
/** @type {twgl.BufferInfo} */
this._lineBufferInfo = twgl.createBufferInfoFromArrays(this._renderer.gl, {
a_position: {
numComponents: 2,
data: this.a_position
},
a_lineColor: {
numComponents: 4,
drawType: this._renderer.gl.STREAM_DRAW,
data: this.a_lineColor
},
a_lineThicknessAndLength: {
numComponents: 2,
drawType: this._renderer.gl.STREAM_DRAW,
data: this.a_lineThicknessAndLength
},
a_penPoints: {
numComponents: 4,
drawType: this._renderer.gl.STREAM_DRAW,
data: this.a_penPoints
}
});

const NO_EFFECTS = 0;
/** @type {twgl.ProgramInfo} */
this._lineShader = this._renderer._shaderManager.getShader(ShaderManager.DRAW_MODE.line, NO_EFFECTS);

// tw: draw region used to preserve texture when resizing
// Draw region used to preserve texture when resizing
this._drawTextureShader = this._renderer._shaderManager.getShader(ShaderManager.DRAW_MODE.default, NO_EFFECTS);
/** @type {object} */
this._drawTextureRegionId = {
enter: () => this._enterDrawTexture(),
exit: () => this._exitDrawTexture()
};

this.a_position_glbuffer = gl.createBuffer();
this.a_position_loc = gl.getAttribLocation(this._lineShader.program, 'a_position');

this.a_lineColor_loc = gl.getAttribLocation(this._lineShader.program, 'a_lineColor');
this.a_lineThicknessAndLength_loc = gl.getAttribLocation(this._lineShader.program, 'a_lineThicknessAndLength');
this.a_penPoints_loc = gl.getAttribLocation(this._lineShader.program, 'a_penPoints');

this.attribute_glbuffer = gl.createBuffer();
this.attribute_index = 0;
this.attribute_data = new Float32Array(PEN_ATTRIBUTE_BUFFER_SIZE);
gl.bindBuffer(gl.ARRAY_BUFFER, this.attribute_glbuffer);
gl.bufferData(gl.ARRAY_BUFFER, this.attribute_data.length * 4, gl.STREAM_DRAW);

if (gl.drawArraysInstanced) {
// WebGL2 has native instanced rendering
this.instancedRendering = true;
this.glDrawArraysInstanced = gl.drawArraysInstanced.bind(gl);
this.glVertexAttribDivisor = gl.vertexAttribDivisor.bind(gl);
} else {
// WebGL1 may have instanced rendering through the ANGLE_instanced_arrays extension
const instancedArraysExtension = gl.getExtension('ANGLE_instanced_arrays');
if (instancedArraysExtension) {
this.instancedRendering = true;
this.glDrawArraysInstanced = instancedArraysExtension.drawArraysInstancedANGLE.bind(
instancedArraysExtension
);
this.glVertexAttribDivisor = instancedArraysExtension.vertexAttribDivisorANGLE.bind(
instancedArraysExtension
);
} else {
// Inefficient but still supported
this.instancedRendering = false;
}
}

if (this.instancedRendering) {
gl.bindBuffer(gl.ARRAY_BUFFER, this.a_position_glbuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
1, 0,
0, 0,
1, 1,
0, 1
]), gl.STATIC_DRAW);
} else {
const positionBuffer = new Float32Array(PEN_ATTRIBUTE_BUFFER_SIZE / PEN_ATTRIBUTE_STRIDE * 2);
for (let i = 0; i < positionBuffer.length; i += 12) {
positionBuffer[i + 0] = 1;
positionBuffer[i + 1] = 0;
positionBuffer[i + 2] = 0;
positionBuffer[i + 3] = 0;
positionBuffer[i + 4] = 1;
positionBuffer[i + 5] = 1;
positionBuffer[i + 6] = 1;
positionBuffer[i + 7] = 1;
positionBuffer[i + 8] = 0;
positionBuffer[i + 9] = 0;
positionBuffer[i + 10] = 0;
positionBuffer[i + 11] = 1;
}
gl.bindBuffer(gl.ARRAY_BUFFER, this.a_position_glbuffer);
gl.bufferData(gl.ARRAY_BUFFER, positionBuffer, gl.STATIC_DRAW);
}

this.onNativeSizeChanged = this.onNativeSizeChanged.bind(this);
this._renderer.on(RenderConstants.Events.NativeSizeChanged, this.onNativeSizeChanged);

Expand Down Expand Up @@ -222,8 +240,6 @@ class PenSkin extends Skin {
* Prepare to draw lines in the _lineOnBufferDrawRegionId region.
*/
_enterDrawLineOnBuffer () {
// tw: reset attributes when starting pen drawing
this._resetAttributeIndexes();
const gl = this._renderer.gl;

twgl.bindFramebufferInfo(gl, this._framebuffer);
Expand All @@ -232,22 +248,27 @@ class PenSkin extends Skin {

const currentShader = this._lineShader;
gl.useProgram(currentShader.program);
twgl.setBuffersAndAttributes(gl, currentShader, this._lineBufferInfo);

const uniforms = {
u_skin: this._texture,
u_stageSize: this._size
};

twgl.setUniforms(currentShader, uniforms);

gl.bindBuffer(gl.ARRAY_BUFFER, this.a_position_glbuffer);
gl.enableVertexAttribArray(this.a_position_loc);
gl.vertexAttribPointer(this.a_position_loc, 2, gl.FLOAT, false, 2 * 4, 0);

this.attribute_index = 0;
}

/**
* Return to a base state from _lineOnBufferDrawRegionId.
*/
_exitDrawLineOnBuffer () {
// tw: flush when exiting pen rendering
if (this.a_lineColorIndex) {
if (this.attribute_index) {
this._flushLines();
}

Expand Down Expand Up @@ -326,19 +347,15 @@ class PenSkin extends Skin {
_drawLineOnBuffer (penAttributes, x0, y0, x1, y1) {
this._renderer.enterDrawRegion(this._lineOnBufferDrawRegionId);

// tw: flush if this line would overflow buffers
// For some reason, looking up the size of a_lineColor with .length is very slow in some browsers.
// We see measurable performance improvements by comparing to a constant instead.
if (this.a_lineColorIndex + 24 > PEN_BUFFER_SIZE_LARGER) {
const iters = this.instancedRendering ? 1 : 6;

// For some reason, looking up the size of a buffer through .length can be slow,
// so use a constant instead.
if (this.attribute_index + (PEN_ATTRIBUTE_STRIDE * iters) > PEN_ATTRIBUTE_BUFFER_SIZE) {
this._flushLines();
}

// Premultiply pen color by pen transparency
const penColor = penAttributes.color4f || DefaultPenAttributes.color4f;
__premultipliedColor[0] = penColor[0] * penColor[3];
__premultipliedColor[1] = penColor[1] * penColor[3];
__premultipliedColor[2] = penColor[2] * penColor[3];
__premultipliedColor[3] = penColor[3];

// tw: apply renderQuality
x0 *= this.renderQuality;
Expand All @@ -357,92 +374,82 @@ class PenSkin extends Skin {

// tw: apply renderQuality
const lineThickness = (penAttributes.diameter || DefaultPenAttributes.diameter) * this.renderQuality;
// tw: write pen draws to buffers where they will be flushed later
for (let i = 0; i < 6; i++) {
this.a_lineColor[this.a_lineColorIndex] = __premultipliedColor[0];
this.a_lineColorIndex++;
this.a_lineColor[this.a_lineColorIndex] = __premultipliedColor[1];
this.a_lineColorIndex++;
this.a_lineColor[this.a_lineColorIndex] = __premultipliedColor[2];
this.a_lineColorIndex++;
this.a_lineColor[this.a_lineColorIndex] = __premultipliedColor[3];
this.a_lineColorIndex++;

this.a_lineThicknessAndLength[this.a_lineThicknessAndLengthIndex] = lineThickness;
this.a_lineThicknessAndLengthIndex++;

this.a_lineThicknessAndLength[this.a_lineThicknessAndLengthIndex] = lineLength;
this.a_lineThicknessAndLengthIndex++;

this.a_penPoints[this.a_penPointsIndex] = x0;
this.a_penPointsIndex++;
this.a_penPoints[this.a_penPointsIndex] = -y0;
this.a_penPointsIndex++;
this.a_penPoints[this.a_penPointsIndex] = lineDiffX;
this.a_penPointsIndex++;
this.a_penPoints[this.a_penPointsIndex] = -lineDiffY;
this.a_penPointsIndex++;
}
}

// tw: resets indexes in the pen drawing buffers
_resetAttributeIndexes () {
this.a_lineColorIndex = 0;
this.a_lineThicknessAndLengthIndex = 0;
this.a_penPointsIndex = 0;
for (let i = 0; i < iters; i++) {
// Pen color sent to the GPU is pre-multiplied by transparency
this.attribute_data[this.attribute_index] = penColor[0] * penColor[3];
this.attribute_index++;
this.attribute_data[this.attribute_index] = penColor[1] * penColor[3];
this.attribute_index++;
this.attribute_data[this.attribute_index] = penColor[2] * penColor[3];
this.attribute_index++;
this.attribute_data[this.attribute_index] = penColor[3];
this.attribute_index++;

this.attribute_data[this.attribute_index] = lineThickness;
this.attribute_index++;

this.attribute_data[this.attribute_index] = lineLength;
this.attribute_index++;

this.attribute_data[this.attribute_index] = x0;
this.attribute_index++;
this.attribute_data[this.attribute_index] = -y0;
this.attribute_index++;
this.attribute_data[this.attribute_index] = lineDiffX;
this.attribute_index++;
this.attribute_data[this.attribute_index] = -lineDiffY;
this.attribute_index++;
}
}

// tw: flushes buffered pen lines to the GPU
_flushLines () {
/** @type {WebGLRenderingContext} */
const gl = this._renderer.gl;

const currentShader = this._lineShader;
gl.bindBuffer(gl.ARRAY_BUFFER, this.attribute_glbuffer);
gl.bufferSubData(gl.ARRAY_BUFFER, 0, new Float32Array(this.attribute_data.buffer, 0, this.attribute_index));

// If only a small amount of data needs to be uploaded, only upload part of the data.
// todo: need to see if this helps and fine tune this number
if (this.a_lineColorIndex < 1000) {
twgl.setAttribInfoBufferFromArray(
gl,
this._lineBufferInfo.attribs.a_lineColor,
new Float32Array(this.a_lineColor.buffer, 0, this.a_lineColorIndex),
0
);
twgl.setAttribInfoBufferFromArray(
gl,
this._lineBufferInfo.attribs.a_penPoints,
new Float32Array(this.a_penPoints.buffer, 0, this.a_penPointsIndex),
0
);
twgl.setAttribInfoBufferFromArray(
gl,
this._lineBufferInfo.attribs.a_lineThicknessAndLength,
new Float32Array(this.a_lineThicknessAndLength.buffer, 0, this.a_lineThicknessAndLengthIndex),
0
gl.enableVertexAttribArray(this.a_lineColor_loc);
gl.vertexAttribPointer(
this.a_lineColor_loc,
4, gl.FLOAT, false,
PEN_ATTRIBUTE_STRIDE_BYTES, 0
);

gl.enableVertexAttribArray(this.a_lineThicknessAndLength_loc);
gl.vertexAttribPointer(
this.a_lineThicknessAndLength_loc,
2, gl.FLOAT, false,
PEN_ATTRIBUTE_STRIDE_BYTES, 4 * 4
);

gl.enableVertexAttribArray(this.a_penPoints_loc);
gl.vertexAttribPointer(
this.a_penPoints_loc,
4, gl.FLOAT, false,
PEN_ATTRIBUTE_STRIDE_BYTES, 6 * 4
);

if (this.instancedRendering) {
this.glVertexAttribDivisor(this.a_lineColor_loc, 1);
this.glVertexAttribDivisor(this.a_lineThicknessAndLength_loc, 1);
this.glVertexAttribDivisor(this.a_penPoints_loc, 1);

this.glDrawArraysInstanced(
gl.TRIANGLE_STRIP,
0, 4,
this.attribute_index / PEN_ATTRIBUTE_STRIDE
);

this.glVertexAttribDivisor(this.a_lineColor_loc, 0);
this.glVertexAttribDivisor(this.a_lineThicknessAndLength_loc, 0);
this.glVertexAttribDivisor(this.a_penPoints_loc, 0);
} else {
twgl.setAttribInfoBufferFromArray(
gl,
this._lineBufferInfo.attribs.a_lineColor,
this.a_lineColor
);
twgl.setAttribInfoBufferFromArray(
gl,
this._lineBufferInfo.attribs.a_penPoints,
this.a_penPoints
);
twgl.setAttribInfoBufferFromArray(
gl,
this._lineBufferInfo.attribs.a_lineThicknessAndLength,
this.a_lineThicknessAndLength
);
gl.drawArrays(gl.TRIANGLES, 0, this.attribute_index / PEN_ATTRIBUTE_STRIDE);
}
// todo: if we skip twgl and do all this buffer stuff ourselves, we can skip some unneeded gl calls
twgl.setBuffersAndAttributes(gl, currentShader, this._lineBufferInfo);

twgl.drawBufferInfo(gl, this._lineBufferInfo, gl.TRIANGLES, this.a_lineThicknessAndLengthIndex / 2);

this._resetAttributeIndexes();

this.attribute_index = 0;
this._silhouetteDirty = true;
}

Expand Down