QShaderProgram Class

class Qt3DRender::QShaderProgram

Encapsulates a Shader Program. More...

Header:	#include <QShaderProgram>
CMake:	find_package(Qt6 COMPONENTS 3drender REQUIRED) target_link_libraries(mytarget PRIVATE Qt6::3drender)
qmake:	QT += 3drender
Since:	Qt 5.5
Instantiated By:	ShaderProgram
Inherits:	Qt3DCore::QNode

• List of all members, including inherited members

Public Types

enum	Format { GLSL, SPIRV }
enum	ShaderType { Vertex, Fragment, TessellationControl, TessellationEvaluation, Geometry, Compute }
enum	Status { NotReady, Ready, Error }

Properties

computeShaderCode : QByteArray format : Format fragmentShaderCode : QByteArray geometryShaderCode : QByteArray log : const QString

status : const Status tessellationControlShaderCode : QByteArray tessellationEvaluationShaderCode : QByteArray vertexShaderCode : QByteArray

Public Functions

QByteArray	computeShaderCode() const
Qt3DRender::QShaderProgram::Format	format() const
QByteArray	fragmentShaderCode() const
QByteArray	geometryShaderCode() const
QString	log() const
void	setFormat(Qt3DRender::QShaderProgram::Format format)
void	setShaderCode(Qt3DRender::QShaderProgram::ShaderType type, const QByteArray &shaderCode)
QByteArray	shaderCode(Qt3DRender::QShaderProgram::ShaderType type) const
Qt3DRender::QShaderProgram::Status	status() const
QByteArray	tessellationControlShaderCode() const
QByteArray	tessellationEvaluationShaderCode() const
QByteArray	vertexShaderCode() const

Public Slots

void	setComputeShaderCode(const QByteArray &computeShaderCode)
void	setFragmentShaderCode(const QByteArray &fragmentShaderCode)
void	setGeometryShaderCode(const QByteArray &geometryShaderCode)
void	setTessellationControlShaderCode(const QByteArray &tessellationControlShaderCode)
void	setTessellationEvaluationShaderCode(const QByteArray &tessellationEvaluationShaderCode)
void	setVertexShaderCode(const QByteArray &vertexShaderCode)

Signals

void	computeShaderCodeChanged(const QByteArray &computeShaderCode)
void	formatChanged(Qt3DRender::QShaderProgram::Format format)
void	fragmentShaderCodeChanged(const QByteArray &fragmentShaderCode)
void	geometryShaderCodeChanged(const QByteArray &geometryShaderCode)
void	logChanged(const QString &log)
void	statusChanged(Qt3DRender::QShaderProgram::Status status)
void	tessellationControlShaderCodeChanged(const QByteArray &tessellationControlShaderCode)
void	tessellationEvaluationShaderCodeChanged(const QByteArray &tessellationEvaluationShaderCode)
void	vertexShaderCodeChanged(const QByteArray &vertexShaderCode)

Static Public Members

QByteArray

loadSource(const QUrl &sourceUrl)

Detailed Description

A shader program consists of several different shaders, such as vertex and fragment shaders.

Qt3D will automatically populate a set of default uniforms if they are encountered during the shader instrospection phase.

Default Uniform	Associated Qt3D Parameter name	GLSL declaration
ModelMatrix	modelMatrix	uniform mat4 modelMatrix;
ViewMatrix	viewMatrix	uniform mat4 viewMatrix;
ProjectionMatrix	projectionMatrix	uniform mat4 projectionMatrix;
ModelViewMatrix	modelView	uniform mat4 modelView;
ViewProjectionMatrix	viewProjectionMatrix	uniform mat4 viewProjectionMatrix;
ModelViewProjectionMatrix	modelViewProjection mvp	uniform mat4 modelViewProjection; uniform mat4 mvp;
InverseModelMatrix	inverseModelMatrix	uniform mat4 inverseModelMatrix;
InverseViewMatrix	inverseViewMatrix	uniform mat4 inverseViewMatrix;
InverseProjectionMatrix	inverseProjectionMatrix	uniform mat4 inverseProjectionMatrix;
InverseModelViewMatrix	inverseModelView	uniform mat4 inverseModelView;
InverseViewProjectionMatrix	inverseViewProjectionMatrix	uniform mat4 inverseViewProjectionMatrix;
InverseModelViewProjectionMatrix	inverseModelViewProjection	uniform mat4 inverseModelViewProjection;
ModelNormalMatrix	modelNormalMatrix	uniform mat3 modelNormalMatrix;
ModelViewNormalMatrix	modelViewNormal	uniform mat3 modelViewNormal;
ViewportMatrix	viewportMatrix	uniform mat4 viewportMatrix;
InverseViewportMatrix	inverseViewportMatrix	uniform mat4 inverseViewportMatrix;
AspectRatio (surface width / surface height)	aspectRatio	uniform float aspectRatio;
Exposure	exposure	uniform float exposure;
Gamma	gamma	uniform float gamma;
Time (in nano seconds)	time	uniform float time;
EyePosition	eyePosition	uniform vec3 eyePosition;
SkinningPalette	skinningPalette[0]	const int maxJoints = 100; uniform mat4 skinningPalette[maxJoints];

RHI Support

When writing GLSL 450 shader code to use with Qt 3D's RHI backend, the default uniforms will be provided as 2 uniform buffer objects.

The binding locations for these is set to bindings 0 for RenderView uniforms and 1 for Command uniforms.

#version 450 core

layout(location = 0) in vec3 vertexPosition;

layout(std140, binding = 0) uniform qt3d_render_view_uniforms {
  mat4 viewMatrix;
  mat4 projectionMatrix;
  mat4 uncorrectedProjectionMatrix;
  mat4 clipCorrectionMatrix;
  mat4 viewProjectionMatrix;
  mat4 inverseViewMatrix;
  mat4 inverseProjectionMatrix;
  mat4 inverseViewProjectionMatrix;
  mat4 viewportMatrix;
  mat4 inverseViewportMatrix;
  vec4 textureTransformMatrix;
  vec3 eyePosition;
  float aspectRatio;
  float gamma;
  float exposure;
  float time;
  float yUpInNDC;
  float yUpInFBO;
};

layout(std140, binding = 1) uniform qt3d_command_uniforms {
  mat4 modelMatrix;
  mat4 inverseModelMatrix;
  mat4 modelViewMatrix;
  mat3 modelNormalMatrix;
  mat4 inverseModelViewMatrix;
  mat4 modelViewProjection;
  mat4 inverseModelViewProjectionMatrix;
};

void main()
{
    gl_Position = (projectionMatrix * viewMatrix * modelMatrix * vertexPosition);
}

For user defined uniform buffer object, use binding starting at 2 or auto to let Qt 3D work out the binding automatically. Make sure to remain consistent between the different shader stages.

#version 450 core

layout(std140, binding = auto) uniform my_uniforms {
  vec4 myColor;
};

layout(location=0) out vec4 fragColor;

void main()
{
    fragColor = myColor;
}

There is no change involved when it comes to feeding values to uniforms.

For the above example, setting myColor could be done with:

QParameter *parameter = new QParameter();
parameter->setName("myColor");
parameter->setValue(QVariant::fromValue(QColor(Qt::blue)));

Textures still have to be defined as standalone uniforms.

#version 450 core

layout(binding=0) uniform sampler2D source;

layout(location=0) out vec4 fragColor;

void main()
{
    fragColor = texture(source, vec2(0.5, 0.5));
}

Member Type Documentation

[since 5.15] enum QShaderProgram::Format

This enum identifies the format of the shader code used.

Constant	Value	Description
Qt3DRender::QShaderProgram::GLSL	0	OpenGL
Qt3DRender::QShaderProgram::SPIRV	1	Vulkan, OpenGL 5

This enum was introduced or modified in Qt 5.15.

enum QShaderProgram::ShaderType

This enum identifies the type of shader used.

Constant	Value	Description
Qt3DRender::QShaderProgram::Vertex	0	Vertex shader
Qt3DRender::QShaderProgram::Fragment	1	Fragment shader
Qt3DRender::QShaderProgram::TessellationControl	2	Tesselation control shader
Qt3DRender::QShaderProgram::TessellationEvaluation	3	Tesselation evaluation shader
Qt3DRender::QShaderProgram::Geometry	4	Geometry shader
Qt3DRender::QShaderProgram::Compute	5	Compute shader

enum QShaderProgram::Status

This enum identifies the status of shader used.

Constant	Value	Description
Qt3DRender::QShaderProgram::NotReady	0	The shader hasn't been compiled and linked yet
Qt3DRender::QShaderProgram::Ready	1	The shader was successfully compiled
Qt3DRender::QShaderProgram::Error	2	An error occurred while compiling the shader

Member Function Documentation

[static invokable] QByteArray QShaderProgram::loadSource(const QUrl &sourceUrl)

Returns the shader code loaded from sourceUrl.

Note: This function can be invoked via the meta-object system and from QML. See Q_INVOKABLE.

void QShaderProgram::setShaderCode(Qt3DRender::QShaderProgram::ShaderType type, const QByteArray &shaderCode)

Sets the shader code for type of shader to the shaderCode.

See also shaderCode().

QByteArray QShaderProgram::shaderCode(Qt3DRender::QShaderProgram::ShaderType type) const

Returns the shader code for type.

See also setShaderCode().

Qt3DRender::QShaderProgram::Status QShaderProgram::status() const

Returns the status of the current shader program.

Note: Getter function for property status.