ChangeLog

2021-10-01  Kimmo Kinnunen  <kkinnunen@apple.com>

        WebGL first clear is lost when scissor is used for preserveDrawingBuffer:true in some conditions

        https://bugs.webkit.org/show_bug.cgi?id=230618

        <rdar://problem/83668270>

        Reviewed by Dean Jackson.

        Disable scissor for the duration of the blit from drawing buffer

        to display buffer.

        Not testable via WebGL conformance test suite as it affects the compositing.

        Test: webgl/gl-clear-preserve-drawing-buffer-bug.html

        * platform/graphics/angle/GraphicsContextGLANGLE.cpp:

        (WebCore::GraphicsContextGLOpenGL::prepareTextureImpl):

2021-09-30  Kimmo Kinnunen  <kkinnunen@apple.com>

        ScopedEGLDefaultDisplay should be removed

Source/WebCore/platform/graphics/angle/GraphicsContextGLANGLE.cpp

@@void GraphicsContextGLOpenGL::prepareTextureImpl()

#else

    if (m_preserveDrawingBufferTexture) {

        // Blit m_preserveDrawingBufferTexture into m_texture.

532 TemporaryANGLESetting scopedScissor(GL_SCISSOR_TEST, GL_FALSE);

533 TemporaryANGLESetting scopedDither(GL_DITHER, GL_FALSE);

        gl::BindFramebuffer(GL_DRAW_FRAMEBUFFER_ANGLE, m_preserveDrawingBufferFBO);

        gl::BindFramebuffer(GL_READ_FRAMEBUFFER_ANGLE, m_fbo);

        gl::BlitFramebufferANGLE(0, 0, m_currentWidth, m_currentHeight, 0, 0, m_currentWidth, m_currentHeight, GL_COLOR_BUFFER_BIT, GL_NEAREST);

LayoutTests/ChangeLog

2021-10-01  Kimmo Kinnunen  <kkinnunen@apple.com>

        WebGL first clear is lost when scissor is used for preserveDrawingBuffer:true in some conditions

        https://bugs.webkit.org/show_bug.cgi?id=230618

        <rdar://problem/83668270>

        Reviewed by Dean Jackson.

        Add a pixel test to verify that scissor is not applied when blitting drawing buffer

        to display buffer in preserveDrawingBuffer: true case.

        * webgl/gl-clear-preserve-drawing-buffer-bug-expected.html: Added.

        * webgl/gl-clear-preserve-drawing-buffer-bug.html: Added.

2021-10-01  Kevin Turner  <kevin_turner@apple.com>

        Add support for pow(), sqrt() and hypot() per https://drafts.csswg.org/css-values-4/#exponent-funcs.

LayoutTests/webgl/gl-clear-preserve-drawing-buffer-bug-expected.html

<!DOCTYPE html>

<html>

<head>

<meta charset="utf-8">

<title>Test for WebGL preserve drawing buffer being affected by scissor.</title>

<script src="resources/webgl_test_files/js/webgl-test-utils.js"> </script>

<style type=text/css>

body { margin: 0 }

</style>

</head>

<body>

<div style="position: absolute; top: 50px; height: 50px; left: 125px; width: 50px; background-color: lime"></div>

<div style="position: absolute; top: 100px; height: 50px; left: 0px; width: 300px; background-color: lime"></div>

</body>

</html>

LayoutTests/webgl/gl-clear-preserve-drawing-buffer-bug.html

<!DOCTYPE html>

<html>

<head>

<meta charset="utf-8">

<title>Test for WebGL preserve drawing buffer being affected by scissor.</title>

<script src="resources/webgl_test_files/js/webgl-test-utils.js"> </script>

<style type=text/css>

body { margin: 0 }

</style>

</head>

<body>

<canvas style="width: 300px; height: 150px" id="c"></canvas>

<script>

"use strict";

var wtu = WebGLTestUtils;

var c = document.getElementById("c");

var scale = window.devicePixelRatio;

c.width = Math.floor(300. * scale);

c.height = Math.floor(150. * scale);

var gl = wtu.create3DContext(c, { preserveDrawingBuffer: true, antialias: false });

gl.enable(gl.SCISSOR_TEST);

gl.clearColor(0., 1., 0., 1);

gl.scissor(0, 0, 300. * scale, 50. * scale);

gl.clear(gl.COLOR_BUFFER_BIT);

gl.scissor(125 * scale, 50 * scale, 50 * scale, 50 * scale);

gl.clear(gl.COLOR_BUFFER_BIT);

if (window.testRunner)

    window.testRunner.dumpAsText(true);

</script>

</body>

</html>