Qt 3D：简单自定义材质 QML 范例

演示在 Qt 3D 中创建自定义材质。

This example demonstrates creating a simple custom material.

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指定场景

The example uses Scene3D to render a scene which will use the custom material. The scene contains a plane model, which uses the custom material.

Entity {
    id: root
    components: [transform, mesh, material]
    SimpleMaterial {
        id: material
        maincolor: "red"
    }
    Transform {
        id: transform
        rotationX: 45
    }
    PlaneMesh {
        id: mesh
        width: 1.0
        height: 1.0
        meshResolution: Qt.size(2, 2)
    }
}

指定材质

The material is specified in simplecustommaterial/SimpleMaterial.qml 使用 Material type. First the material specifies parameters, which are mapped to the corresponding uniforms in the shaders so that they can be changed from the qml.

property color maincolor: Qt.rgba(0.0, 0.0, 0.0, 1.0)
parameters: [
    Parameter {
        name: "maincolor"
        value: Qt.vector3d(root.maincolor.r, root.maincolor.g, root.maincolor.b)
    }
]

Next we specify which shaders are loaded. Separate versions of the shaders are provided for OpenGL ES 2 and OpenGL renderers.

property string vertex: "qrc:/shaders/gl3/simpleColor.vert"
property string fragment: "qrc:/shaders/gl3/simpleColor.frag"
property string vertexRHI: "qrc:/shaders/gl45/simpleColor.vert"
property string fragmentRHI: "qrc:/shaders/gl45/simpleColor.frag"
property string vertexES: "qrc:/shaders/es2/simpleColor.vert"
property string fragmentES: "qrc:/shaders/es2/simpleColor.frag"

In the vertex shader we simply transform the position by the transformation matrices.

void main()
{
    // Transform position, normal, and tangent to world coords
    worldPosition = vec3(modelMatrix * vec4(vertexPosition, 1.0));
    // Calculate vertex position in clip coordinates
    gl_Position = mvp * vec4(worldPosition, 1.0);
}

In the fragment shader we simply set the fragment color to be the maincolor specified in the material.

uniform vec3 maincolor;
void main()
{
    //output color from material
    fragColor = vec4(maincolor,1.0);
}

Next, we create ShaderPrograms from the shaders.

ShaderProgram {
    id: gl3Shader
    vertexShaderCode: loadSource(parent.vertex)
    fragmentShaderCode: loadSource(parent.fragment)
}
ShaderProgram {
    id: es2Shader
    vertexShaderCode: loadSource(parent.vertexES)
    fragmentShaderCode: loadSource(parent.fragmentES)
}
ShaderProgram {
    id: rhiShader
    vertexShaderCode: loadSource(parent.vertexRHI)
    fragmentShaderCode: loadSource(parent.fragmentRHI)
}

Finally the shader programs are used in the Techniques corresponding to a specific Api profile.

// OpenGL 3.1
Technique {
    filterKeys: [forward]
    graphicsApiFilter {
        api: GraphicsApiFilter.OpenGL
        profile: GraphicsApiFilter.CoreProfile
        majorVersion: 3
        minorVersion: 1
    }
    renderPasses: RenderPass {
        shaderProgram: gl3Shader
    }
},

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