ShaderProgram QML Type

Encapsulates a Shader Program.

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The Qt Company Ltd.

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Publié le 27 décembre 2024 - Mis à jour le 27 décembre 2024

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ShaderProgram QML Type▲

Import Statement: import Qt3D.Render 2.6
Instantiates:: QShaderProgram

Detailed Description▲

ShaderProgram class encapsulates a shader program. 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.

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#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.

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#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:

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Parameter { name: "myColor"; value: "blue" }

Textures still have to be defined as standalone uniforms.

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#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));
}

Property Documentation▲

computeShaderCode : string▲

Holds the compute shader code used by this shader program.

computeShaderGraph : string▲

Holds the URL to the compute shader graph used by this shader program builder.

format : enumeration▲

Holds the format of the code provided on the ShaderProgram. The default is ShaderProgram.GLSL

fragmentShaderCode : string▲

Holds the fragment shader code used by this shader program.

fragmentShaderGraph : string▲

Holds the URL to the fragment shader graph used by this shader program builder.

geometryShaderCode : string▲

Holds the geometry shader code used by this shader program.

geometryShaderGraph : string▲

Holds the URL to the geometry shader graph used by this shader program builder.

[read-only] log : string▲

Holds the log of the current shader program. This is useful to diagnose a compilation failure of the shader program.

[read-only] status : enumeration▲

Holds the status of the current shader program.

tessellationControlShaderCode : string▲

Holds the tesselation control shader code used by this shader program.

tessellationControlShaderGraph : string▲

Holds the URL to the tesselation control shader graph used by this shader program builder.

tessellationEvaluationShaderCode : string▲

Holds the tesselation evaluation shader code used by this shader program.

tessellationEvaluationShaderGraph : string▲

Holds the URL to the tesselation evaluation shader graph used by this shader program builder.

vertexShaderCode : string▲

Holds the vertex shader code used by this shader program.

vertexShaderGraph : string▲

Holds the URL to the vertex shader graph used by this shader program builder.

Method Documentation▲

string loadSource(url sourceUrl)▲

Returns the shader code loaded from sourceUrl.

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