Qt 3D: Simple Custom Material QML Example | Qt 3D 5.15.19

- Qt 5.15
- Qt 3D
- Qt 3D: Simple Custom Material QML Example
- Qt 5.15.19 Reference Documentation

# Qt 3D: Simple Custom Material QML Example

Demonstrates creating a custom material in Qt 3D.

This example demonstrates creating a simple custom material.

#### Running the Example

To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.

#### Specifying the Scene

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)
         }
     }

#### Specifying the Material

The material is specified in `simplecustommaterial/SimpleMaterial.qml` using 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 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)
     }

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
         }
     },

Example project @ code.qt.io