Lazlo, Thank you very much for your reply.
This will definitely definitely help. I will get back here if I don’t make any progress in the next couple of days. Thank you very much! Best regards, Nuno > On 17 Feb 2021, at 11:19, Laszlo Agocs <laszlo.ag...@qt.io> wrote: > > Hi Nuno, > > Check your implementation of type(). It should return something unique for > all the different 'source' values (i.e. for every different vertex+fragment > shader combinations). Right now, with the same static type object is returns, > VSMaterial::createShader() is only ever called once, so all instances of > VSMaterial will use the same VSMaterialShader regardless of the different > fragment shader code in 'source', which explains the effect you are seeing. > > An example of a dynamic implementation of type() you are looking for can be > found in ShaderEffect: > https://code.qt.io/cgit/qt/qtdeclarative.git/tree/src/quick/items/qquickopenglshadereffectnode.cpp?h=5.15#n389 > > <https://code.qt.io/cgit/qt/qtdeclarative.git/tree/src/quick/items/qquickopenglshadereffectnode.cpp?h=5.15#n389> > https://code.qt.io/cgit/qt/qtdeclarative.git/tree/src/quick/items/qquickopenglshadereffectnode.cpp?h=5.15#n453 > > <https://code.qt.io/cgit/qt/qtdeclarative.git/tree/src/quick/items/qquickopenglshadereffectnode.cpp?h=5.15#n453> > > Best regards, > Laszlo > > From: Interest <interest-boun...@qt-project.org> on behalf of Nuno Santos > <nuno.san...@imaginando.pt> > Sent: Monday, February 15, 2021 3:36 PM > To: interestqt-project.org <interest@qt-project.org> > Subject: [Interest] Using QSGMaterial & QSGMaterialShader with multiple > shaders > > Hi, > > I’m trying to make a shader gallery using a GridView where the model is an > array of shaders path. > > Then, a custom QQuickView, instantiates a custom QSGGeometryNode with a > material that extends QSGMaterial. The QSGMaterial creates the shader: > > I’m having a problem though. All the items draw the first shader in the list. > Shader A draws everything red, shader B draws everything blue. > > If model = [A, B], the two items show as red, if I swap the model order to > [B, A], the two items show blue. > > I’ve added debug and there are classes being instantiated correctly for each > item, and the right shader source is being used for each one, but it seems > that only the first shader that is passed to the model seems to be loaded or > active. > > Is there any gotcha in the way QSGMateria and QSGMaterialShader are used? > > Code for material and material shader are included below. > > Thanks! > > Nuno > > VSMaterial::VSMaterial(QString source) : > _source(source) > { > setFlag(RequiresFullMatrixExceptTranslate, true); > setFlag(Blending, true); > } > > int VSMaterial::compare(const QSGMaterial *other) const > { > Q_UNUSED(other) > > return 0; > } > > QSGMaterialType *VSMaterial::type() const > { > static QSGMaterialType type; > > return &type; > } > > QSGMaterialShader *VSMaterial::createShader() const > { > return new VSMaterialShader(_source); > } > > VSMaterialShader::VSMaterialShader(QString source) > : QSGMaterialShader() > { > setShaderSourceFile(QOpenGLShader::Vertex, > QString(":/shaders/rectangle.vert")); > setShaderSourceFile(QOpenGLShader::Fragment, source); > } > > void VSMaterialShader::updateState(const QSGMaterialShader::RenderState > &state, QSGMaterial *newEffect, QSGMaterial *oldEffect) > { > Q_UNUSED(newEffect) > > if (state.isOpacityDirty()) > program()->setUniformValue(m_opacityLoc, state.opacity()); > > if (state.isMatrixDirty()) > program()->setUniformValue(m_matrixLoc, state.combinedMatrix()); > > if (oldEffect == 0) > { > // The viewport is constant, so set the pixel size uniform only once. > QRect r = state.viewportRect(); > program()->setUniformValue(m_pixelSizeLoc, 2.0f / r.width(), 2.0f / > r.height()); > } > > VSMaterial *material = static_cast<VSMaterial*>(newEffect); > > program()->setUniformValue(_idPositionX, material->positionX); > program()->setUniformValue(_idPositionY, material->positionY); > } > > const char * const *VSMaterialShader::attributeNames() const > { > static char const *const attributes[] = { > "vertex", > "vertexColor", > "vertexOffset", > 0 > }; > > return attributes; > } > > void VSMaterialShader::initialize() > { > m_matrixLoc = program()->uniformLocation("matrix"); > m_opacityLoc = program()->uniformLocation("opacity"); > m_pixelSizeLoc = program()->uniformLocation("pixelSize"); > > _idPositionX = program()->uniformLocation("positionX"); > _idPositionY = program()->uniformLocation("positionY"); > }
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