gl_engine: rewrite the blending shader #3081

RuiwenTang · 2024-12-27T09:45:14Z

Completely rewrite the GL backend shader to support advance blending and correct the blending behavior.
Now the GL backend has the same blending result as SKIA and CanvasRenderingContext2D in browers did.

The formula is referenced from https://www.w3.org/TR/compositing-1/#porterduffcompositingoperators

Note this change make the Blending example rendered different with other backend, but the result is consistent with SKIA, which I believe is correct.

The current rendering result can reference this issue #3072
It also fix the blending issue in Lottie animation: #2799

hermet · 2025-01-07T08:03:40Z

@RuiwenTang Please check this:

hermet · 2025-01-07T14:27:18Z

hermet · 2025-01-09T11:46:03Z

@RuiwenTang I'd like to recommend separating the incorrect equation (ColorBurn, ColorEdge) from the destination alpha issue. We can apply the equation correction commit first.

sw:

gl:

RuiwenTang · 2025-01-09T12:13:29Z

@hermet

This is what I have been saying. I think this PR fixes all the problems of GLEngine in Blending, and I think that all of the result is correct.

hermet · 2025-01-09T12:31:04Z

@hermet This is what I have been saying. I think this PR fixes all the problems of GLEngine in Blending, and I think that all of the result is correct.

@RuiwenTang

Separating commits per problems. That is our basic policy.
You know, I didn't say that is the wrong result. I requested you to see me further the layer level scene blending first to put them together fix. If it's not harder for you, Please humor me.

Copilot

Pull Request Overview

This PR rewrites the GL backend shader blending implementation to support advanced blending modes and achieve consistency with SKIA and CanvasRenderingContext2D. Key changes include:

Revamped blending shader code with new modes (Lighten, Darken) and reworked blend formulas.
Updates to the renderer API to accept a BlendMethod parameter for complex blending.
Modifications to render task and render pass handling to accommodate viewport changes and render target usage.

Reviewed Changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/renderer/gl_engine/tvgGlShaderSrc.h	Added new shader definitions for LIGHTEN and DARKEN blend modes.
src/renderer/gl_engine/tvgGlShaderSrc.cpp	Updated blending algorithm implementations and removed legacy blend function macros.
src/renderer/gl_engine/tvgGlRenderer.h	Updated blending functions’ signatures to include a BlendMethod parameter.
src/renderer/gl_engine/tvgGlRenderer.cpp	Integrated the new blend modes throughout the complex blending pipeline.
src/renderer/gl_engine/tvgGlRenderTask.{h,cpp}	Modified GlComplexBlendTask to remove stencilTask and added viewport setters.
src/renderer/gl_engine/tvgGlRenderTarget.{h,cpp}	Introduced in-use flag handling for render targets.
src/renderer/gl_engine/tvgGlRenderPass.{h,cpp}	Updated render pass constructors and viewport handling.
src/renderer/gl_engine/tvgGlProgram.{h,cpp}	Added caching for uniform locations and blocks.
src/renderer/gl_engine/tvgGlCommon.h	Added a BlendMethod member to GlCompositor for compositing logic.

Copilot · 2025-05-09T16:01:32Z

src/renderer/gl_engine/tvgGlShaderSrc.cpp

    void main()
    {
        vec4 srcColor = texture(uSrcTexture, vUV);
        vec4 dstColor = texture(uDstTexture, vUV);
-        FragColor = hardLightBlend(srcColor, dstColor);
+


The parameter order for blend_overlay is reversed compared to the former hard light blend function; consider adding an inline comment to explain this intentional inversion and the resulting blending effect.

Suggested change

// The parameter order for blend_overlay is intentionally reversed compared to the former hard light blend function.

// This inversion ensures that the blending effect prioritizes the destination color (dstColor) over the source color (srcColor).

Copilot · 2025-05-09T16:01:33Z

src/renderer/gl_engine/tvgGlRenderer.cpp

@@ -539,26 +533,26 @@ GlRenderPass* GlRenderer::currentPass()
    return mRenderPassStack.last();
 }



It would be helpful to document the purpose of the new 'blend' parameter and list which BlendMethod values trigger complex blending; this can improve clarity for future maintenance.

Suggested change

/**

* Initiates complex blending for the given blend method and render regions.

*

* @param blend The blending method to be applied. Complex blending is triggered

* for all BlendMethod values except BlendMethod::Normal and BlendMethod::Add.

* Examples of complex blending methods include Multiply, Screen, and Overlay.

* @param vp The viewport region where blending is applied.

* @param bounds The bounding region for the blending operation.

* @return True if complex blending is initiated, false otherwise.

*/

Copilot · 2025-05-09T16:01:33Z

src/renderer/gl_engine/tvgGlRenderTask.cpp

@@ -332,12 +332,11 @@ void GlSimpleBlendTask::run()
    glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
 }



Since the mStencilTask parameter has been removed from the GlComplexBlendTask constructor and related logic, please update the class comments/documentation to clearly reflect this change and its impact on blending workflow.

Suggested change

/**

* GlComplexBlendTask

*

* This class is responsible for handling complex blending operations.

* Note: The mStencilTask parameter has been removed from the constructor and related logic.

* As a result, stencil-based blending is no longer part of this task's workflow.

* The blending workflow now relies solely on the provided GlComposeTask and render targets.

*/

Copilot · 2025-05-09T16:01:33Z

src/renderer/gl_engine/tvgGlRenderTarget.cpp

@@ -118,15 +122,15 @@ GlRenderTarget* GlRenderTargetPool::getRenderTarget(const RenderRegion& vp, GLui
    for (uint32_t i = 0; i < mPool.count; i++) {
        auto rt = mPool[i];


Review the render target reuse logic with the newly introduced in-use flag to ensure targets are correctly marked and released; adding a brief comment on the lifecycle management of render targets would aid future debugging.

Suggested change

auto rt = mPool[i];

auto rt = mPool[i];

// Check if the render target matches the required dimensions and is not in use.

// If found, mark it as in use and return it.

Completely rewrite the GL backend shader to support advance blending and correct the blending behavior. Now the GL backend has the same blending result as SKIA and CanvasRenderingContext2D in browers did. The formula is referenced from: https://www.w3.org/TR/compositing-1/#porterduffcompositingoperators issue: #2799

hermet · 2025-07-03T10:16:18Z

@SergeyLebedkin Please review this,

Animation looks leaking gpu resources after this PR.

github-actions bot added the cpu Software render backend label Dec 27, 2024

RuiwenTang mentioned this pull request Dec 27, 2024

renderer: incorrect BlendMode behaviors #3072

Open

hermet added the enhancement Improve features label Dec 27, 2024

hermet assigned RuiwenTang Dec 27, 2024

hermet requested a review from SergeyLebedkin December 30, 2024 07:20

RuiwenTang force-pushed the ruiwen/composite_blending branch 2 times, most recently from 2c438bf to a7e2b61 Compare January 3, 2025 08:11

hermet force-pushed the ruiwen/composite_blending branch 3 times, most recently from d07b491 to 4a7ce3a Compare January 14, 2025 03:20

hermet force-pushed the ruiwen/composite_blending branch from 4a7ce3a to f30a2a9 Compare February 7, 2025 04:24

github-actions bot added the raster label Feb 7, 2025

hermet force-pushed the main branch from 7b6e42e to f64fb08 Compare February 9, 2025 16:36

hermet removed the raster label Feb 20, 2025

hermet force-pushed the main branch 2 times, most recently from b234c07 to f1e9ce0 Compare March 17, 2025 06:28

hermet force-pushed the main branch 2 times, most recently from 964770d to dadd7a9 Compare March 31, 2025 14:34

hermet force-pushed the ruiwen/composite_blending branch from f30a2a9 to 71434d6 Compare May 9, 2025 15:59

github-actions bot added gl OpenGL/WebGL render backend and removed cpu Software render backend labels May 9, 2025

hermet requested a review from Copilot May 9, 2025 15:59

Copilot AI reviewed May 9, 2025

View reviewed changes

hermet force-pushed the ruiwen/composite_blending branch from 71434d6 to 3c88423 Compare May 12, 2025 04:27

hermet force-pushed the main branch from a6c06d1 to dfc7d26 Compare June 8, 2025 02:54

hermet force-pushed the main branch 5 times, most recently from 9b6c8bc to a6ffb7a Compare June 23, 2025 07:12

hermet force-pushed the main branch 5 times, most recently from 7ceb794 to 43923a5 Compare June 25, 2025 15:59

hermet force-pushed the ruiwen/composite_blending branch from 3c88423 to bfe7071 Compare June 30, 2025 03:09

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Uh oh!

gl_engine: rewrite the blending shader #3081

gl_engine: rewrite the blending shader #3081

Uh oh!

RuiwenTang commented Dec 27, 2024

Uh oh!

hermet commented Jan 7, 2025 •

edited

Loading

Uh oh!

hermet commented Jan 7, 2025 •

edited

Loading

Uh oh!

hermet commented Jan 9, 2025

Uh oh!

RuiwenTang commented Jan 9, 2025

Uh oh!

hermet commented Jan 9, 2025 •

edited

Loading

Uh oh!

Copilot AI left a comment

Uh oh!

Copilot AI May 9, 2025

Uh oh!

Copilot AI May 9, 2025

Uh oh!

Copilot AI May 9, 2025

Uh oh!

Copilot AI May 9, 2025

Uh oh!

hermet commented Jul 3, 2025

Uh oh!

Uh oh!



	// The parameter order for blend_overlay is intentionally reversed compared to the former hard light blend function.
	// This inversion ensures that the blending effect prioritizes the destination color (dstColor) over the source color (srcColor).

		@@ -539,26 +533,26 @@ GlRenderPass* GlRenderer::currentPass()
		return mRenderPassStack.last();
		}

+/**
+ * Initiates complex blending for the given blend method and render regions.
+ *
+ * @param blend The blending method to be applied. Complex blending is triggered
+ *              for all BlendMethod values except BlendMethod::Normal and BlendMethod::Add.
+ *              Examples of complex blending methods include Multiply, Screen, and Overlay.
+ * @param vp The viewport region where blending is applied.
+ * @param bounds The bounding region for the blending operation.
+ * @return True if complex blending is initiated, false otherwise.
+ */

		@@ -332,12 +332,11 @@ void GlSimpleBlendTask::run()
		glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
		}

+/**
+ * GlComplexBlendTask
+ *
+ * This class is responsible for handling complex blending operations.
+ * Note: The mStencilTask parameter has been removed from the constructor and related logic.
+ *       As a result, stencil-based blending is no longer part of this task's workflow.
+ *       The blending workflow now relies solely on the provided GlComposeTask and render targets.
+ */

		@@ -118,15 +122,15 @@ GlRenderTarget* GlRenderTargetPool::getRenderTarget(const RenderRegion& vp, GLui
		for (uint32_t i = 0; i < mPool.count; i++) {
		auto rt = mPool[i];

Uh oh!

gl_engine: rewrite the blending shader #3081

Are you sure you want to change the base?

gl_engine: rewrite the blending shader #3081

Uh oh!

Conversation

RuiwenTang commented Dec 27, 2024

Uh oh!

hermet commented Jan 7, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

hermet commented Jan 7, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

hermet commented Jan 9, 2025

Uh oh!

RuiwenTang commented Jan 9, 2025

Uh oh!

hermet commented Jan 9, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull Request Overview

Reviewed Changes

Uh oh!

Copilot AI May 9, 2025

Choose a reason for hiding this comment

Uh oh!

Copilot AI May 9, 2025

Choose a reason for hiding this comment

Uh oh!

Copilot AI May 9, 2025

Choose a reason for hiding this comment

Uh oh!

Copilot AI May 9, 2025

Choose a reason for hiding this comment

Uh oh!

hermet commented Jul 3, 2025

Uh oh!

Uh oh!

hermet commented Jan 7, 2025 •

edited

Loading

hermet commented Jan 7, 2025 •

edited

Loading

hermet commented Jan 9, 2025 •

edited

Loading