[libkwineffects/kwinglutils] Calculate correct srcY0 and srcY1 in GLRenderTarget::blitFromFramebuffer
Summary:
There are several spaces that have to be considered in GLRenderTarget::blitFromFramebuffer:
- KWin logical space: the origin is located at the global top-left corner
- display space: the origin is located at the top-left corner of monitor/display
- OpenGL screen space: the origin is located at the bottom-left corner of monitor/display
Given s, which is in the KWin logical space, we have to transform it to the display space, then to the OpenGL screen space:
- KWin logical space -> display space: y' = s.y() - s_virtualScreenGeometry.y()
- display space -> OpenGL screen space: y'' = s_virtualScreenGeometry.height() - y'
Overall, srcY0 and srcY1 should be written as follows:
srcY0 = s_virtualScreenGeometry.height() - (s.y() - s_virtualScreenGeometry.y() + s.height()) srcY1 = s_virtualScreenGeometry.height() - (s.y() - s_virtualScreenGeometry.y())
Test Plan:
Tweak background contrast effect to use GLRenderTarget::blitFromFramebuffer
diff --git a/effects/backgroundcontrast/contrast.cpp b/effects/backgroundcontrast/contrast.cpp index f920fcd88..5247d83b8 100644 --- a/effects/backgroundcontrast/contrast.cpp +++ b/effects/backgroundcontrast/contrast.cpp @@ -447,11 +447,10 @@ void ContrastEffect::doContrast(EffectWindow *w, const QRegion& shape, const QRe GLTexture scratch(GL_RGBA8, r.width() * scale, r.height() * scale); scratch.setFilter(GL_LINEAR); scratch.setWrapMode(GL_CLAMP_TO_EDGE); - scratch.bind(); - const QRect sg = GLRenderTarget::virtualScreenGeometry(); - glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, (r.x() - sg.x()) * scale, (sg.height() - sg.y() - r.y() - r.height()) * scale, - scratch.width(), scratch.height()); + GLRenderTarget scratchTarget(scratch); + scratchTarget.blitFromFramebuffer(r); + scratch.bind(); // Draw the texture on the offscreen framebuffer object, while blurring it horizontally
GLRenderTarget::blitFromFramebuffer without this change:
Reviewers: KWin, fredrik, davidedmundson
Reviewed By: KWin, davidedmundson
Subscribers: kpiwowarski, davidedmundson, kwin
Tags: KWin
Differential Revision: https://phabricator.kde.org/D12452