在QML中控制纹理三维物体的不透明度

Question

在QML中，我对QT3D有点陌生，我试图控制纹理的 3D对象的不透明度。为了做到这一点，我正在使用simpleqml3d测试项目。

我玩过这些材料，但没能让它起作用。这是我从IronMan.qml测试项目修改的simpleqml3d实体：

import Qt3D.Core 2.0
import Qt3D.Render 2.0
import Qt3D.Extras 2.0

Entity {
    id: root

    property real x: 0
    property real y: 0
    property real z: 0
    property real scale: 1.0

    Texture2D{
        id: texture
        TextureImage {
            source: "qrc:/man.png"
        }
    }

    //COPY RenderableEntity.qml in your project!!!!!!
    RenderableEntity{
        id: chest
        source: "qrc:/man.obj" //Path to iron man model. You can open it with 3D Builder on Windows 10
        position: Qt.vector3d(root.x, root.y, root.z)
        scale:  root.scale

//        material: DiffuseMapMaterial {
//            id: material
//            diffuse:  texture
//            specular: Qt.rgba( 0.2, 0.2, 0.2, 1.0 )
//            shininess: 2.0
//        }

//        material: DiffuseMapMaterial {
//            diffuse:  texture
//            specular: Qt.rgba( 0.2, 0.2, 0.2, 1.0 )
//            shininess: 2.0
//        }

//        material: DiffuseSpecularMaterial {
//            alphaBlending: true
//            diffuse: Qt.rgba(0.2, 0.2, 0.2, 0.0)//texture
//            specular: texture//Qt.rgba(0.2, 0.2, 0.2, 0.5)
//            shininess: 2.0
//        }

//        material: PhongMaterial {
//            ambient: Qt.rgba( 1, 0, 0, 0 )
//            diffuse: Qt.rgba( 1, 0, 0, 0 )
//            shininess: 50
//        }

//        material: PhongAlphaMaterial {
//            alpha: 0.0
//            diffuse: Qt.rgba(0.2, 0.2, 0.2, 0.0)//texture
//            specular: Qt.rgba(0.2, 0.2, 0.2, 0.0)
//            shininess: 2.0
//        }

        material: PhongAlphaMaterial {
            alpha: 0.0
            ambient: Qt.rgba( 1, 0, 0, 0 )
            diffuse: Qt.rgba( 1, 0, 0, 0 )
            shininess: 50
        }
    }
}

评论材料是我玩过的材料。即使使用PhongAlphaMaterial，我也无法工作，当不透明设置为0.0时，模型仍然显示如下：

​

​

有人能帮我控制纹理三维物体的不透明度，但也不放松纹理？

编辑：

我已经接受了Florian的答案，因为这个答案是基于Github存储库的，所以我认为最好在StackOverflow上也有代码，以防他的分叉存储库分支发生什么不好的事情。因此，我将在这里张贴的资源，使项目充分发挥作用。

simpleqml3d.pro

TEMPLATE = app

QT += core gui widgets 3dcore 3drender 3dinput 3dquick qml quick 3dquickextras
CONFIG += c++11

SOURCES += main.cpp

RESOURCES += resources.qrc

# Additional import path used to resolve QML modules in Qt Creator's code model
QML_IMPORT_PATH =

# Additional import path used to resolve QML modules just for Qt Quick Designer
QML_DESIGNER_IMPORT_PATH =

# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

main.cpp

/****************************************************************************
**
** Copyright (C) 2014 Klaralvdalens Datakonsult AB (KDAB).
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt3D module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include <Qt3DQuickExtras/qt3dquickwindow.h>
#include <Qt3DQuick/QQmlAspectEngine>
#include <QGuiApplication>
#include <QQmlEngine>
#include <QQmlContext>

int main(int argc, char* argv[])
{
    QGuiApplication app(argc, argv);
    Qt3DExtras::Quick::Qt3DQuickWindow view;

        // Expose the window as a context property so we can set the aspect ratio
    view.engine()->qmlEngine()->rootContext()->setContextProperty("_window", &view);
    view.setSource(QUrl("qrc:/main.qml"));
    view.show();

    return app.exec();
}

resources.qrc

<RCC>
    <qresource prefix="/">
        <file>main.qml</file>
        <file>IronMan.qml</file>
        <file>man.obj</file>
        <file>man.png</file>
        <file>TextureAlphaMaterial.qml</file>
    </qresource>
    <qresource prefix="/shaders">
        <file>unlittexture.frag</file>
        <file>unlittexture.vert</file>
    </qresource>
</RCC>

main.qml

/****************************************************************************
**
** Copyright (C) 2016 Klaralvdalens Datakonsult AB (KDAB).
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt3D module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/

import QtQuick 2.1
import Qt3D.Core 2.0
import Qt3D.Render 2.9
import Qt3D.Input 2.0
import Qt3D.Extras 2.9

Entity {
    id: root
    objectName: "root"

    // Use the renderer configuration specified in ForwardRenderer.qml
    // and render from the mainCamera
    components: [
        RenderSettings {
            activeFrameGraph: RenderSurfaceSelector {
                id: renderSurfaceSelector

                CameraSelector {
                    id: cameraSelector
                    camera: camera
                    Viewport {
                        id: viewport
                        normalizedRect: Qt.rect(0, 0, 1, 1)
                        ClearBuffers {
                            buffers: ClearBuffers.AllBuffers
                            clearColor: "white"
                            NoDraw{}
                        }
                        LayerFilter {
                            layers: [opaqueLayer]

                        }
                        LayerFilter {
                            layers: [opaqueLayer]
                            filterMode: LayerFilter.DiscardAllMatchingLayers
                            NoDepthMask {}
                        }
                    }
                }
            }
        },
        InputSettings { }
    ]

    Camera {
        id: camera
        projectionType: CameraLens.PerspectiveProjection
        fieldOfView: 45
        nearPlane : 0.1
        farPlane : 1000.0
        position: Qt.vector3d( 0.0, 4.0, -5.0 )
        upVector: Qt.vector3d( 0.0, 1.0, 0.0 )
        viewCenter: Qt.vector3d( 0.0, 0.0, 0.0 )
    }

    FirstPersonCameraController { camera: camera }

    Entity {
        components: [
            PointLight {
                enabled: parent.enabled
                color: "black"
                intensity: 0
            }
        ]
    }

    Entity {
        PlaneMesh {
            id: groundMesh
            width: 50
            height: width
            meshResolution: Qt.size(2, 2)
        }

        Transform {
            id: groundTransform
            translation: Qt.vector3d(0, 0, 0)
        }

        Layer {
            id: opaqueLayer
        }

        PhongMaterial {
            id: material
            diffuse: Qt.rgba( 0.5, 0.5, 0.5, 1 )
            ambient: Qt.rgba( 0.5, 0.5, 0.5, 1 )
        }

        components: [
            groundMesh,
            groundTransform,
            material,
            opaqueLayer
        ]
    }
    IronMan {
        id: ironMan
    }
}

IronMan.qml

import Qt3D.Core 2.0
import Qt3D.Render 2.0
import Qt3D.Extras 2.0

import QtQml 2.14

Entity {
    id: root

    property vector3d position: Qt.vector3d(0, 0, 0)
    property real scale: 1.0
    property real rotationAngle: 0.0
    property vector3d rotationAxis: Qt.vector3d(1, 0, 0)
    property alias source: mesh.source
    property Material material

    components: [ transform, mesh, material ]

    Transform {
        id: transform
        scale: root.scale
        rotation: fromAxisAndAngle(root.rotationAxis, root.rotationAngle)
        translation: root.position
    }

    Mesh {
        id: mesh
        source: "qrc:/man.obj"
    }

    material: TextureAlphaMaterial {
        id: material

        opacity: 0.5
    }
}

TextureAlphaMaterial.qml

import Qt3D.Core 2.0
import Qt3D.Render 2.0

Material {
    id: root

    property real opacity: 1.

    parameters: [
        Parameter {
            name: "diffuseTexture"
            value: Texture2D {
                textureImages: [
                    TextureImage {
                        source: "qrc:/man.png"
                    }
                ]
            }
        }
    ]

    effect: Effect {
        id: rootEffect

        parameters: [
            Parameter
            {
                name: "opacity"
                value: root.opacity
            }
        ]
        techniques: [
            Technique {
                graphicsApiFilter {
                    api: GraphicsApiFilter.OpenGL
                    profile: GraphicsApiFilter.CoreProfile
                    majorVersion: 3
                    minorVersion: 1
                }

                filterKeys: [ FilterKey { name: "renderingStyle"; value: "forward" } ]

                renderPasses: [
                    RenderPass {
                        shaderProgram: ShaderProgram {
                            vertexShaderCode:   loadSource("qrc:/shaders/unlittexture.vert")
                            fragmentShaderCode: loadSource("qrc:/shaders/unlittexture.frag")
                        } 
                        renderStates: [
                            DepthTest {
                                depthFunction: DepthTest.LessOrEqual
                            },
                            NoDepthMask {
                            },
                            BlendEquation {
                                blendFunction: BlendEquation.Add
                            },
                            BlendEquationArguments {
                                sourceRgb: BlendEquationArguments.One
                                destinationRgb: BlendEquationArguments.OneMinusSourceAlpha
                                sourceAlpha: BlendEquationArguments.One
                                destinationAlpha: BlendEquationArguments.OneMinusSourceAlpha
                            }
                        ]
                    }
                ]
            }
        ]
    }
}

unlittexture.frag

#version 150 core

uniform sampler2D diffuseTexture;
uniform float opacity;

in vec3 position;
in vec2 texCoord;

out vec4 fragColor;


void main()
{
    fragColor = vec4(texture(diffuseTexture, texCoord).xyz * opacity, opacity);
}

unlittexture.vert

#version 150 core

in vec3 vertexPosition;
in vec2 vertexTexCoord;

out vec3 position;
out vec2 texCoord;

uniform mat4 modelView;
uniform mat4 mvp;

void main()
{
    vec3 t = vec3(vertexTexCoord, 1.0);
    texCoord = (t / t.z).xy;
    position = vec3(modelView * vec4(vertexPosition, 1.0));

    gl_Position = mvp * vec4(vertexPosition, 1.0);
}

注意：

您可以分别用任何3D模型(使用Blender或任何其他3D软件导出到obj )或映射纹理替换man.obj和man.png。然而，它们可以在弗洛里安储存库或特里波拉佩特储存库上找到。

这是最终结果：

​

​

Answer 1

编辑2

我修改了你的计划。它现在以透明的纹理显示模型，您可以在GitHub上找到它。一定要查看分支transparent_texture。

我没有实现允许动态设置透明性的功能，但我认为您可以从示例开始自己实现。该模型也没有照明，即只有纹理显示没有任何闪电，但应该很容易实现一些简单的phong闪电，看看其他的Qt3D材料。

原始答案

Qt3D不提供透明纹理对象的材料，这意味着您必须自己实现它。我过会儿再谈这个。

简单透明度

关于您的透明度问题，我玩了一下代码，让下面的代码正常工作，但是没有按钮：

main.cpp

#include <Qt3DQuickExtras/qt3dquickwindow.h>
#include <Qt3DQuick/QQmlAspectEngine>
#include <QGuiApplication>
#include <QQmlEngine>
#include <QQmlContext>

int main(int argc, char* argv[])
{
    QGuiApplication app(argc, argv);
    Qt3DExtras::Quick::Qt3DQuickWindow view;

    view.engine()->qmlEngine()->rootContext()->setContextProperty("_window", &view);
    view.setSource(QUrl("qrc:/main.qml"));
    view.show();

    return app.exec();
}

main.qml

import QtQuick 2.1
import Qt3D.Core 2.0
import Qt3D.Render 2.9
import Qt3D.Input 2.0
import Qt3D.Extras 2.9

Entity {
    id: root
    objectName: "root"

    // Use the renderer configuration specified in ForwardRenderer.qml
    // and render from the mainCamera
    components: [
        RenderSettings {
            activeFrameGraph: RenderSurfaceSelector {
                id: renderSurfaceSelector

                CameraSelector {
                    id: cameraSelector
                    camera: camera
                    Viewport {
                        id: viewport
                        normalizedRect: Qt.rect(0, 0, 1, 1)
                        ClearBuffers {
                            buffers: ClearBuffers.AllBuffers
                            clearColor: "white"
                            NoDraw{}
                        }
                        LayerFilter {
                            layers: [opaqueLayer]

                        }
                        LayerFilter {
                            layers: [opaqueLayer]
                            filterMode: LayerFilter.DiscardAllMatchingLayers
                        }
                    }
                }
            }
        },
        // Event Source will be set by the Qt3DQuickWindow
        InputSettings { }
    ]

    Camera {
        id: camera
        projectionType: CameraLens.PerspectiveProjection
        fieldOfView: 45
        nearPlane : 0.1
        farPlane : 1000.0
        position: Qt.vector3d( 0.0, 4.0, -5.0 )
        upVector: Qt.vector3d( 0.0, 1.0, 0.0 )
        viewCenter: Qt.vector3d( 0.0, 0.0, 0.0 )
    }

    FirstPersonCameraController { camera: camera }

    Entity {
        components: [
            PointLight {
                enabled: parent.enabled
                color: "black"
                intensity: 0
            }
        ]
    }

    Entity {
        PlaneMesh {
            id: groundMesh
            width: 50
            height: width
            meshResolution: Qt.size(2, 2)
        }

        Transform {
            id: groundTransform
            translation: Qt.vector3d(0, 0, 0)
        }

        Layer {
            id: opaqueLayer
        }

        PhongMaterial {
            id: material
            diffuse: Qt.rgba( 0.5, 0.5, 0.5, 1 )
            ambient: Qt.rgba( 0.5, 0.5, 0.5, 1 )
        }

        components: [
            groundMesh,
            groundTransform,
            material,
            opaqueLayer
        ]
    }

    Entity {
        id: sphere1

        Mesh {
            id: man
            source: "qrc:/man.obj"
        }

        components: [
            man,
            matSphere1Material
        ]

        PhongAlphaMaterial {
            id: matSphere1Material
            alpha: 0.1
            ambient: Qt.rgba( 1, 1, 0, 0.0 )
            diffuse: Qt.rgba( 1, 1, 0, 0.0 )
            shininess: 50
        }
    }
}

我简化了您的示例，以找出问题所在，看起来您在main.cpp中使用了错误的QML引擎。但是我建议您尝试一下Scene3DView示例，因为透明度可以与类似的设置一起工作(如果您需要UI中的按钮)。我经常使用这些例子并根据我的需要对它们进行修改。我只想让你从我提供的代码开始。

如果您问自己为什么我在那里有LayerFilters，请查看我的回答，这解释了为什么当您在场景中有透明对象时，这是必要的。

透明纹理对象

这更困难(不幸的是，我没有时间提供示例代码，可能会在某些事情不起作用时开始并提出问题)。在这里你必须实现你自己的着色器。Qt3D根本不提供任何考虑alpha的读取实现。一个经常帮助我的存储库是q3dpostproc存储库。您可以看到如何构建您自己的Qt3D材料，加载您自己的着色器并将参数传递给它们。

还有高级定制材料的例子，它可以提供很多帮助，如何创建自定义着色器和传递参数。

如果要查看如何在着色器中纹理对象，请签出QTextureMaterial着色机及其代码。我试着在QML中重新创建它，但是它没有立即工作。

我建议您使用q3dpostproc代码并尝试纹理其中的一个对象(项目的结构有点复杂，因为它只是一个展示，但过一段时间这一切都是有意义的)。它已经有了一个使用纹理的着色器，因为它首先将所有东西绘制到屏幕外的缓冲区，然后使用该纹理绘制屏幕。在您成功地用自己的着色器对其中一个对象进行纹理处理之后，您可以在其中执行如下操作：

fragColor = vec4(texture(...).xyz, 0.5);

这应该会给你一个透明的纹理。当您想要正确地亮起纹理时，您可能需要在最后用更精细的东西替换texture(...).xyz。但要做到这一点，您可以查看Qt3D GitHub存储库中的phong着色器，它是我链接的，也可以是从这个储存库或其他地方从互联网上获得的。

我希望这些信息能有所帮助。

编辑1

我修改了q3dpostproc代码以在GitHub分支中显示透明纹理。这些物体还没有被点燃，但这应该会使它们的功能变得清晰。