QShaderDescription Class

  #version 440

  layout(location = 0) in vec4 position;
  layout(location = 1) in vec3 color;
  layout(location = 0) out vec3 v_color;

  layout(std140, binding = 0) uniform buf {
      mat4 mvp;
      float opacity;
  } ubuf;

  out gl_PerVertex { vec4 gl_Position; };

  void main()
  {
      v_color = color;
      gl_Position = ubuf.mvp * position;
  }

  {
      "inputs": [
          {
              "location": 1,
              "name": "color",
              "type": "vec3"
          },
          {
              "location": 0,
              "name": "position",
              "type": "vec4"
          }
      ],
      "outputs": [
          {
              "location": 0,
              "name": "v_color",
              "type": "vec3"
          }
      ],
      "uniformBlocks": [
          {
              "binding": 0,
              "blockName": "buf",
              "members": [
                  {
                      "matrixStride": 16,
                      "name": "mvp",
                      "offset": 0,
                      "size": 64,
                      "type": "mat4"
                  },
                  {
                      "name": "opacity",
                      "offset": 64,
                      "size": 4,
                      "type": "float"
                  }
              ],
              "set": 0,
              "size": 68,
              "structName": "ubuf"
          }
      ]
  }

Member Function Documentation

QShaderDescription::QShaderDescription()

Constructs a new, empty QShaderDescription.

Note: Being empty implies that isValid() returns false for the newly constructed instance.

QShaderDescription::~QShaderDescription()

Destructor.

QVector<QShaderDescription::InOutVariable> QShaderDescription::combinedImageSamplers() const

Returns the list of combined image samplers

With GLSL/Vulkan shaders as source a layout(binding = 1) uniform sampler2D tex; uniform generates the following: (shown as textual JSON here)

  "combinedImageSamplers": [
       {
           "binding": 1,
           "name": "tex",
           "set": 0,
           "type": "sampler2D"
       }
   ]

This does not mean that other language versions of the shader must also use a combined image sampler, especially considering that the concept may not exist everywhere. For instance, a HLSL version will likely just use a Texture2D and SamplerState object with registers t1 and s1, respectively.

[static] QShaderDescription QShaderDescription::fromBinaryJson(const QByteArray &data)

Deserializes the given binary JSON data and returns a new QShaderDescription.

QVector<QShaderDescription::InOutVariable> QShaderDescription::inputVariables() const

Returns the list of input variables. This includes vertex inputs (sometimes called attributes) for the vertex stage, and inputs for other stages (sometimes called varyings).

bool QShaderDescription::isValid() const

Returns true if the QShaderDescription contains at least one entry in one of the variable and block lists.

QVector<QShaderDescription::InOutVariable> QShaderDescription::outputVariables() const

Returns the list of output variables.

QVector<QShaderDescription::PushConstantBlock> QShaderDescription::pushConstantBlocks() const

Returns the list of push constant blocks.

Note: Avoid relying on push constant blocks for shaders that are to be used in combination with the Qt Rendering Hardware Interface since that currently has no support for them.

QVector<QShaderDescription::StorageBlock> QShaderDescription::storageBlocks() const

Returns the list of shader storage blocks.

For example, with GLSL/Vulkan shaders as source, the declaration

  struct Stuff {
      vec2 a;
      vec2 b;
  };
  layout(std140, binding = 0) buffer StuffSsbo {
      vec4 whatever;
      Stuff stuff[];
  } buf;

generates the following: (shown as textual JSON here)

  "storageBlocks": [ {
      "binding": 0,
      "blockName": "StuffSsbo",
      "instanceName": "buf",
      "knownSize": 16,
      "members": [
          {
              "name": "whatever",
              "offset": 0,
              "size": 16,
              "type": "vec4"
          },
          {
              "arrayDims": [
                  0
              ],
              "name": "stuff",
              "offset": 16,
              "size": 0,
              "structMembers": [
                  {
                      "name": "a",
                      "offset": 0,
                      "size": 8,
                      "type": "vec2"
                  },
                  {
                      "name": "b",
                      "offset": 8,
                      "size": 8,
                      "type": "vec2"
                  }
              ],
              "type": "struct"
          }
      ],
      "set": 0
  } ]

Note: The size of the last member in the storage block is undefined. This shows up as size 0 and an array dimension of [0]. The storage block's knownSize excludes the size of the last member since that will only be known at run time.

Note: SSBOs are not available with some graphics APIs, such as, OpenGL 2.x or OpenGL ES older than 3.1.

QVector<QShaderDescription::InOutVariable> QShaderDescription::storageImages() const

Returns the list of image variables.

These will likely occur in compute shaders. For example, layout (binding = 0, rgba8) uniform readonly image2D inputImage; generates the following: (shown as textual JSON here)

  "storageImages": [
       {
           "binding": 0,
           "imageFormat": "rgba8",
           "name": "inputImage",
           "set": 0,
           "type": "image2D"
       }
   ]

Note: Separate image objects are not compatible with some graphics APIs, such as, OpenGL 2.x or OpenGL ES older than 3.1.

QByteArray QShaderDescription::toBinaryJson() const

Returns a serialized binary version of the data.

See also toJson().

QByteArray QShaderDescription::toJson() const

Returns a serialized JSON text version of the data.

Note: There is no deserialization method provided for JSON text.

See also toBinaryJson().

QVector<QShaderDescription::UniformBlock> QShaderDescription::uniformBlocks() const

Returns the list of uniform blocks.