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Don't use GL_REPEAT for image-brush drawing on OpenGL ES2

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OpenGL ES2 doesn't support NPOT textures in combination with GL_REPEAT,
so for OpenGL ES2 we use a custom program that emulates repeat by taking
the fractional part of the texture coordinates.

This is not enough though, as merely setting GL_TEXTURE_WRAP_x to GL_REPEAT
with a NPOT texture is an error in some implementations, so we have to
guard the call to updateTextureFilter() in updateBrushTexture() with
a check for OpenGL ES2 and use GL_CLAMP_TO_EDGE instead.

This fixes missing/black backgrounds in the diagramscene example on iOS.

Change-Id: I5020090b5f17faeb06dcab9dc0292459e021af30
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>
This commit is contained in:
Tor Arne Vestbø 2013-05-02 12:27:19 +02:00 committed by The Qt Project
parent 9504516847
commit 8dfeb1c374
1 changed files with 9 additions and 1 deletions
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10
src/gui/opengl/qopenglpaintengine.cpp
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@ -226,9 +226,17 @@ void QOpenGL2PaintEngineExPrivate::updateBrushTexture()
if (currentBrushPixmap.width() > max_texture_size || currentBrushPixmap.height() > max_texture_size)
currentBrushPixmap = currentBrushPixmap.scaled(max_texture_size, max_texture_size, Qt::KeepAspectRatio);
#if defined(QT_OPENGL_ES_2)
// OpenGL ES does not support GL_REPEAT wrap modes for NPOT textures. So instead,
// we emulate GL_REPEAT by only taking the fractional part of the texture coords
// in the qopenglslTextureBrushSrcFragmentShader program.
GLuint wrapMode = GL_CLAMP_TO_EDGE;
#else
GLuint wrapMode = GL_REPEAT;
#endif
funcs.glActiveTexture(GL_TEXTURE0 + QT_BRUSH_TEXTURE_UNIT);
QOpenGLTextureCache::cacheForContext(ctx)->bindTexture(ctx, currentBrushPixmap);
updateTextureFilter(GL_TEXTURE_2D, GL_REPEAT, q->state()->renderHints & QPainter::SmoothPixmapTransform);
updateTextureFilter(GL_TEXTURE_2D, wrapMode, q->state()->renderHints & QPainter::SmoothPixmapTransform);
textureInvertedY = false;
}
brushTextureDirty = false;