Base component for creating custom materials used to shade models. 更多...
导入语句: | import QtQuick3D |
继承: | Material |
The custom material allows using custom shader code for a material, enabling programmability on graphics shader level. A vertex, fragment, or both shaders can be provided. The
vertexShader
and
fragmentShader
properties are URLs, referencing files containing shader snippets, and work very similarly to
ShaderEffect
or
Image.source
. Only the
file
and
qrc
schemes are supported with custom materials. It is also possible to omit the
file
scheme, allowing to specify a relative path in a convenient way. Such a path is resolved relative to the component's (the
.qml
file's) location.
For a getting started guide to custom materials, see the page 可编程材质、效果、几何图形和纹理数据 .
Consider the following versions of the same scene. On the left, the cylinder is using a built-in, non-programmable material. Such materials are configurable through a wide range of properties, but there is no further control given over the shaders that are generated under the hood. On the right, the same cylinder is now associated with a CustomMaterial referencing application-provided vertex and fragment shader snippets. This allows inserting custom, application-specific logic into the vertex shader to transform the geometry, and to determine certain color properties in a custom manner in the fragment shader. As this is a shaded custom material, the cylinder still participates in the scene lighting normally.
View3D { anchors.fill: parent PerspectiveCamera { id: camera position: Qt.vector3d(0, 0, 600) } camera: camera DirectionalLight { position: Qt.vector3d(-500, 500, -100) color: Qt.rgba(0.2, 0.2, 0.2, 1.0) ambientColor: Qt.rgba(0.1, 0.1, 0.1, 1.0) } Model { source: "#Cylinder" eulerRotation: Qt.vector3d(30, 30, 0) scale: Qt.vector3d(1.5, 1.5, 1.5) materials: [ DefaultMaterial { diffuseColor: Qt.rgba(0, 1, 0, 1) } ] } } |
View3D { anchors.fill: parent PerspectiveCamera { id: camera position: Qt.vector3d(0, 0, 600) } camera: camera DirectionalLight { position: Qt.vector3d(-500, 500, -100) color: Qt.rgba(0.2, 0.2, 0.2, 1.0) ambientColor: Qt.rgba(0.1, 0.1, 0.1, 1.0) } Model { source: "#Cylinder" eulerRotation: Qt.vector3d(30, 30, 0) scale: Qt.vector3d(1.5, 1.5, 1.5) materials: [ CustomMaterial { vertexShader: "material.vert" fragmentShader: "material.frag" property real uTime property real uAmplitude: 50 NumberAnimation on uTime { from: 0; to: 100; duration: 10000; loops: -1 } } ] } } |
Let's assume that the shader snippets in
material.vert
and
material.frag
are the following:
void MAIN() { VERTEX.x += sin(uTime + VERTEX.y) * uAmplitude; } |
void MAIN() { BASE_COLOR = vec4(0.0, 1.0, 0.0, 1.0); } |
Notice how
uTime
and
uAmplitude
are properties of the CustomMaterial element. They can change values and get animated normally, the values will be exposed to the shaders automatically without any further action from the developer.
The result is a cylinder that animates its vertices:
There are two main types of custom materials. This is specified by the
shadingMode
property. In
unshaded
custom materials the fragment shader outputs a single
vec4
color, ignoring lights, light probes, shadowing in the scene. In
shaded
materials the shader is expected to implement certain functions and work with built-in variables to take lighting and shadow contribution into account.
The default choice is typically a shaded material, this is reflected in the default value of the
shadingMode
property. This fits materials that needs to transform vertices or other incoming data from the geometry, or determine values like
BASE_COLOR
or
EMISSIVE_COLOR
in a custom manner, perhaps by sampling
SCREEN_TEXTURE
or
DEPTH_TEXTURE
, while still reciving light and shadow contributions from the scene. Additionally, such materials can also override and reimplement the equations used to calculate the contributions from directional, point, and other lights. The application-provided shader snippets are heavily amended by the Qt Quick 3D engine under the hood, in order to provide the features, such as lighting, the standard materials have.
Unshaded materials are useful when the object's appearance is determined completely by the custom shader code. The shaders for such materials receive minimal additions by the engine, and therefore it is completely up to the shader to determine the final fragment color. This gives more freedom, but also limits possiblities to integrate with other elements of the scene, such as lights.
注意: Shader code is always provided using Vulkan-style GLSL, regardless of the graphics API used by Qt at run time.
注意: The vertex and fragment shader code provided by the material are not full, complete GLSL shaders on their own. Rather, they provide a set of functions, which are then amended with further shader code by the engine.
The dynamic properties of the CustomMaterial can be changed and animated using QML and Qt Quick facilities, and the values are exposed to the shaders automatically. This in practice is very similar ShaderEffect . The following list shows how properties are mapped:
"green"
are in sRGB color space as well, and the same conversion is performed for all color properties of
DefaultMaterial
and
PrincipledMaterial
, so this behavior of CustomMaterial matches those. Unlike Qt Quick, for Qt Quick 3D linearizing is essential as there will typically be tonemapping performed on the 3D scene.
w
注意: When a uniform referenced in the shader code does not have a corresponding property, it will cause a shader compilation error when processing the material at run time. There are some exceptions to this, such as, sampler uniforms, that get a dummy texture bound when no corresponding QML property is present, but as a general rule, all uniforms and samplers must have a corresponding property declared in the CustomMaterial object.
The following is an example of an unshaded custom material.
CustomMaterial { // These properties are automatically exposed to the shaders property real time: 0.0 property real amplitude: 5.0 property real alpha: 1.0 property TextureInput tex: TextureInput { enabled: true texture: Texture { source: "image.png" } } shadingMode: CustomMaterial.Unshaded sourceBlend: alpha < 1.0 ? CustomMaterial.SrcAlpha : CustomMaterial.NoBlend destinationBlend: alpha < 1.0 ? CustomMaterial.OneMinusSrcAlpha : CustomMaterial.NoBlend cullMode: CustomMaterial.BackFaceCulling vertexShader: "customshader.vert" fragmentShader: "customshader.frag" }
With the above example, the unshaded vertex and fragment shaders snippets could look like the following. Note how the shaders do not, and must not, declare uniforms or vertex inputs as that is taken care of by Qt when assembling the final shader code.
VARYING vec3 pos; VARYING vec2 texcoord; void MAIN() { pos = VERTEX; pos.x += sin(time * 4.0 + pos.y) * amplitude; texcoord = UV0; POSITION = MODELVIEWPROJECTION_MATRIX * vec4(pos, 1.0); }
VARYING vec3 pos; VARYING vec2 texcoord; void MAIN() { vec4 c = texture(tex, texcoord); FRAGCOLOR = vec4(pos.x * 0.02, pos.y * 0.02, pos.z * 0.02, alpha) * c; }
The following special, uppercase keywords are available:
MAIN
. Providing this function is mandatory in shader snippets for unshaded custom materials.
A
shaded
material
augments
the shader code that would be generated by a
PrincipledMaterial
. Unlike unshaded materials, that provide almost all logic for the vertex and fragment shader main functions on their own, preventing adding generated code for lighting, shadowing, global illumination, etc., shaded materials let shader generation happen normally, as if the CustomMaterial was a
PrincipledMaterial
. The vertex and fragment shader snippets are expected to provide optional functions that are then invoked at certain points, giving them the possibility to customize the colors and other values that are then used for calculating lighting and the final fragment color.
Rather than implementing just a
MAIN
function, the fragment shader for a shaded custom material can implement multiple functions. All functions, including
MAIN
, are optional to implement in shaded custom materials. An empty shader snippet, or, even, not specifying the
vertexShader
or
fragmentShader
properties at all can be perfectly valid too.
The following functions can be implemented in a vertex shader snippet:
void MAIN()
When present, this function is called in order to set the value of
POSITION
, the vec4 output from the vertex shader, and, optionally, to modify the values of
VERTEX
,
COLOR
,
NORMAL
,
UV0
,
UV1
,
TANGENT
,
BINORMAL
,
JOINTS
,和
WEIGHTS
. Unlike in unshaded materials, writing to these makes sense because the modified values are then taken into account in the rest of the generated shader code (whereas for unshaded materials there is no additional shader code generated). For example, if the custom vertex shader displaces the vertices or the normals, it will want to store the modified values to
VERTEX
or
NORMAL
, to achieve correct lighting calculations afterwards. Additionally, the function can write to variables defined with
VARYING
in order to pass interpolated data to the fragment shader. When this function or a redefinition of
POSITION
is not present,
POSITION
is calculated based on
VERTEX
and
MODELVIEWPROJECTION_MATRIX
, just like a
PrincipledMaterial
would do.
Example, with relying both on QML properties exposed as uniforms, and also passing data to the fragment shader:
VARYING vec3 vNormal; VARYING vec3 vViewVec; void MAIN() { VERTEX.x += sin(uTime * 4.0 + VERTEX.y) * uAmplitude; vNormal = normalize(NORMAL_MATRIX * NORMAL); vViewVec = CAMERA_POSITION - (MODEL_MATRIX * vec4(VERTEX, 1.0)).xyz; POSITION = MODELVIEWPROJECTION_MATRIX * vec4(VERTEX, 1.0); }
注意:
In the above example, assigning a value to
POSITION
is optional as the usage in this case is identical to the default behavior.
The following functions can be implemented in a fragment shader snippet:
void MAIN()
When present, this function is called to set the values of the special writable variables
BASE_COLOR
,
METALNESS
,
ROUGHNESS
,
SPECULAR_AMOUNT
, NORMAL, and
FRESNEL_POWER
.
One common use case is to set the value of
BASE_COLOR
based on sampling a texture, be it a base color map,
SCREEN_TEXTURE
, or some other kind of source. This can be relevant and convenient especially when no custom light processor functions are implemented. Setting
BASE_COLOR.a
to something other than the default 1.0 allows affecting the final alpha value of the fragment. (note that this will often require also enabling alpha blending in
sourceBlend
and
destinationBlend
)
Another scenario is when there is no custom
SPECULAR_LIGHT
function provided, or when there is a light probe set in the
SceneEnvironment
. The metalness, roughness, and other values that affect the specular contribution calculation can be set in
MAIN
to their desired custom values.
The function can write to the following special variables. The values written to these will typically be either hardcoded or be calculated based on QML properties mapped to uniforms. The semantics are identical to PrincipledMaterial .
BASE_COLOR
- The base color and material alpha value. Corresponds to the
built-in materials' color property
. When light processor functions are not implemented, it can be convenient to set a custom base color in
MAIN
because that is then taken into account in the default lighting calculations. The default value is
vec4(1.0)
, meaning white with an alpha of 1.0. The alpha value effects the final alpha of the fragment. The final alpha value is the object (model) opacity multiplied by the base color alpha. When specifying the value directly in shader code, not relying on uniform values exposed from
color
properties in QML, be aware that it is up to the shader to perform the sRGB to linear conversion, if needed. For example, assuming a
vec3 color
and
float alpha
this can be achieved like the following:
float C1 = 0.305306011; vec3 C2 = vec3(0.682171111, 0.682171111, 0.682171111); vec3 C3 = vec3(0.012522878, 0.012522878, 0.012522878); BASE_COLOR = vec4(rgb * (rgb * (rgb * C1 + C2) + C3), alpha);
EMISSIVE_COLOR
- The color of self-illumination. Corresponds to the built-in materials' emissive color which is combined by
built-in materials's emissiveFactor property
and
built-in materials's emissiveMap property
。默认值为
vec3(0.0)
. When specifying the value directly in shader code, not relying on uniform values exposed from
color
properties in QML, be aware that it is up to the shader to perform the sRGB to linear conversion, if needed.
METALNESS
Metalness amount in range 0.0 - 1.0. The default value is 0. Must be set to a non-zero value to have effect.
ROUGHNESS
Roughness value in range 0.0 - 1.0. The default value is 0.
FRESNEL_POWER
Specifies the fresnel power. A typical value, and also the default, is
5.0
as that is what a
PrincipledMaterial
would use.
SPECULAR_AMOUNT
Specular amount in range 0.0 - 1.0. The default value is
0.5
, matching
PrincipledMaterial::specularAmount
. Must be set to a non-zero value to have effect.
NORMAL
- The normal that comes from the vertex shader in world space. While this property has the same initial value as
VAR_WORLD_NORMAL
, only changing the value of
NORMAL
will have an effect on lighting.
TANGENT
- The tanget that comes from the vertex shader in world space. This value is potentially adjusted for double-sidedness.
BINORMAL
- The binormal that comes from the vertex shader in world space. This value is potentially adjusted for double-sidedness.
UV0
- The first set of texture coordinates from the vertex shader. This property is readonly in the fragment shader.
UV1
- The second set of texture coordinates from the vertex shader. This property is readonly in the fragment shader.
注意:
Unlike with unshaded materials, the fragment
MAIN
for a shaded material has no direct control over
FRAGCOLOR
. Rather, it is the
DIFFUSE
and
SPECULAR
values written in the light processor functions that decide what the final fragment color is. When a light processor function is not implemented, the relevant default shading calculations are performed as with a
PrincipledMaterial
, taking
BASE_COLOR
and other values from the list above into account.
An example of a simple, metallic custom material shader could be the following:
void MAIN() { METALNESS = 1.0; ROUGHNESS = 0.5; FRESNEL_POWER = 5.0; }
Another example, where the base color and alpha are set by sampling a texture:
VARYING vec2 texcoord; void MAIN() { BASE_COLOR = texture(uColorMap, texcoord); }
void AMBIENT_LIGHT()
When present, this function is called once for each fragment. The task of the function is to add the total ambient contribution to a writable special variable
DIFFUSE
. It can of course choose to calculate a different value, or not touch
DIFFUSE
at all (to ignore ambient lighting completely). When this function is not present at all, the ambient contribution is calculated normally, like a
PrincipledMaterial
would do.
The function can write to the following special variables:
DIFFUSE
Accumulates the diffuse light contributions, per fragment. The light processor functions will typically add (
+=
) to it, since overwriting the value would lose the contribution from other lights.
The function can read the following special variables, in addition to the matrix (such as,
MODEL_MATRIX
) and vector (such as,
CAMERA_POSITION
) uniforms from the table above:
TOTAL_AMBIENT_COLOR
The total ambient contribution in the scene.
范例:
void AMBIENT_LIGHT() { DIFFUSE += TOTAL_AMBIENT_COLOR; }
void DIRECTIONAL_LIGHT()
When present, this function is called for each active directional light in the scene for each fragment. The task of the function is to add the diffuse contribution to a writable special variable
DIFFUSE
. The function can also choose to do nothing, in which case diffuse contributions from directional lights are ignored. When the function is not present at all, the diffuse contributions from directional lights are accumulated normally, like a
PrincipledMaterial
would do.
The function can write to the following special variables:
DIFFUSE
Accumulates the diffuse light contributions, per fragment. The light processor functions will typically add (
+=
) to it, since overwriting the value would lose the contribution from other lights.
The function can read the following special variables, in addition to the matrix (such as,
MODEL_MATRIX
) and vector (such as,
CAMERA_POSITION
) uniforms from the table above:
LIGHT_COLOR
Diffuse light color.
SHADOW_CONTRIB
Shadow contribution, or 1.0 if not shadowed at all or not reciving shadows.
TO_LIGHT_DIR
Vector pointing towards the light source.
NORMAL
The normal vector in world space.
BASE_COLOR
The base color and material alpha value.
METALNESS
The Metalness amount.
ROUGHNESS
The Roughness amount.
范例:
void DIRECTIONAL_LIGHT() { DIFFUSE += LIGHT_COLOR * SHADOW_CONTRIB * vec3(max(0.0, dot(normalize(VAR_WORLD_NORMAL), TO_LIGHT_DIR))); }
void POINT_LIGHT()
When present, this function is called for each active point light in the scene for each fragment. The task of the function is to add the diffuse contribution to a writable special variable
DIFFUSE
. The function can also choose to do nothing, in which case diffuse contributions from point lights are ignored. When the function is not present at all, the diffuse contributions from point lights are accumulated normally, like a
PrincipledMaterial
would do.
The function can write to the following special variables:
DIFFUSE
Accumulates the diffuse light contributions, per fragment.
The function can read the following special variables, in addition to the matrix (such as,
MODEL_MATRIX
) and vector (such as,
CAMERA_POSITION
) uniforms from the table above:
LIGHT_COLOR
Diffuse light color.
LIGHT_ATTENUATION
Light attenuation.
SHADOW_CONTRIB
Shadow contribution, or 1.0 if not shadowed at all or not reciving shadows.
TO_LIGHT_DIR
Vector pointing towards the light source.
NORMAL
The normal vector in world space.
BASE_COLOR
The base color and material alpha value.
METALNESS
The Metalness amount.
ROUGHNESS
The Roughness amount.
范例:
void POINT_LIGHT() { DIFFUSE += LIGHT_COLOR * LIGHT_ATTENUATION * SHADOW_CONTRIB * vec3(max(0.0, dot(normalize(VAR_WORLD_NORMAL), TO_LIGHT_DIR))); }
void SPOT_LIGHT()
When present, this function is called for each active spot light in the scene for each fragment. The task of the function is to add the diffuse contribution to a writable special variable
DIFFUSE
. The function can also choose to do nothing, in which case diffuse contributions from spot lights are ignored. When the function is not present at all, the diffuse contributions from spot lights are accumulated normally, like a
PrincipledMaterial
would do.
The function can write to the following special variables:
DIFFUSE
Accumulates the diffuse light contributions, per fragment.
The function can read the following special variables, in addition to the matrix (such as,
MODEL_MATRIX
) and vector (such as,
CAMERA_POSITION
) uniforms from the table above:
LIGHT_COLOR
Diffuse light color.
LIGHT_ATTENUATION
Light attenuation.
SHADOW_CONTRIB
Shadow contribution, or 1.0 if not shadowed at all or not reciving shadows.
TO_LIGHT_DIR
Vector pointing towards the light source.
SPOT_FACTOR
Spot light factor.
NORMAL
The normal vector in world space.
BASE_COLOR
The base color and material alpha value.
METALNESS
The Metalness amount.
ROUGHNESS
The Roughness amount.
范例:
void SPOT_LIGHT() { DIFFUSE += LIGHT_COLOR * LIGHT_ATTENUATION * SPOT_FACTOR * SHADOW_CONTRIB * vec3(max(0.0, dot(normalize(VAR_WORLD_NORMAL), TO_LIGHT_DIR))); }
void SPECULAR_LIGHT()
When present, this function is called for each active light in the scene for each fragment. The task of the function is to add the specular contribution to a writable special variable
SPECULAR
. The function can also choose to do nothing, in which case specular contributions from lights are ignored. When the function is not present at all, the specular contributions from lights are accumulated normally, like a
PrincipledMaterial
would do.
The function can write to the following special variables:
SPECULAR
Accumulates the specular light contributions, per frament. The light processor functions will typically add (
+=
) to it, since overwriting the value would lose the contribution from other lights.
The function can read the following special variables, in addition to the matrix (such as,
MODEL_MATRIX
) and vector (such as,
CAMERA_POSITION
) uniforms from the table above:
LIGHT_COLOR
Specular light color.
LIGHT_ATTENUATION
Light attenuation. For directional lights the value is 1.0. For spot lights the value is the same as
LIGHT_ATTENUATION * SPOT_FACTOR
of
void SPOT_LIGHT()
.
SHADOW_CONTRIB
Shadow contribution, or 1.0 if not shadowed at all or not reciving shadows.
FRESNEL_CONTRIB
Fresnel contribution from built in Fresnel calculation.
TO_LIGHT_DIR
Vector pointing towards the light source.
NORMAL
The normal vector in world space.
BASE_COLOR
The base color and material alpha value.
METALNESS
The Metalness amount.
ROUGHNESS
The Roughness amount.
SPECULAR_AMOUNT
The specular amount. This value will be between 0.0 and 1.0 will be the same value set in the custom
MAIN
function. This value will useful for calculating Fresnel contributions when not using the built-in Fresnel contribution provided by
FRESNEL_CONTRIB
.
void SPECULAR_LIGHT() { vec3 H = normalize(VIEW_VECTOR + TO_LIGHT_DIR); float cosAlpha = max(0.0, dot(H, normalize(NORMAL))); float shine = pow(cosAlpha, exp2(15.0 * (1.0 - ROUGHNESS) + 1.0) * 0.25); SPECULAR += shine * LIGHT_COLOR * FRESNEL_CONTRIB * SHADOW_CONTRIB * LIGHT_ATTENUATION; }
void POST_PROCESS()
When present, this function is called at the end of the fragment pipeline. The task of the function is to finalize
COLOR_SUM
with final diffuse, specular and emissive terms. Unlike
FRAGCOLOR
for a unshaded material,
COLOR_SUM
will be automatically tonemapped before written to the framebuffer. For debugging purposes it is sometimes useful to output a value that should not be treated as a color. To avoid the tonemapping distorting this value it can be disabled by setting the
tonemapMode
特性到
TonemapModeNone
The function can write to the following special variables:
COLOR_SUM
the output from the fragment shader. The default value is vec4(DIFFUSE.rgb + SPECULAR + EMISSIVE, DIFFUSE.a)
The function can read the following special variables.
DIFFUSE
The final diffuse term of the fragment pipeline.
SPECULAR
The final specular term of the fragment pipeline.
EMISSIVE
The final emissive term of the fragment pipeline.
UV0
- The first set of texture coordinates from the vertex shader.
UV1
- The second set of texture coordinates from the vertex shader.
void POST_PROCESS() { float center_x = textureSize(SCREEN_TEXTURE, 0).x * 0.5; if (gl_FragCoord.x > center_x) COLOR_SUM = DIFFUSE; else COLOR_SUM = vec4(EMISSIVE, DIFFUSE.a); }
Additional variables can be delivered from the MAIN function to the others. The
SHARED_VARS
keyword can be used for defining new custom variables. These user-defined variables can be accessed with SHARED.<variable name>.
For example, a shaded custom material can fetch a shared value in the MAIN and use it in other functions.
SHARED_VARS { vec3 colorThreshold; }; void MAIN() { BASE_COLOR = texture(baseColorMap, UV0); SHARED.colorThreshold = texture(thresholdMap, UV0).rgb; } void DIRECTIONAL_LIGHT() { if (DIFFUSE >= SHARED.colorThreshold) { DIFFUSE = SHARED.colorThreshold; return; } DIFFUSE += LIGHT_COLOR * SHADOW_CONTRIB; }
注意: SHARED can be written on all the functions without POST_PROCESS but it is safe to write it on MAIN and read on the other functions.
注意: A recommended use case to write SHARED on LIGHT functions is reseting it on MAIN first and then accumulating it on each LIGHT functions.
SHARED_VARS { float sheenIntensity; float sheenRoughness; vec3 sheenColor; vec3 outSheenColor; }; void MAIN() { ... vec4 tex = texture(uSheenMap, UV0); SHARED.sheenColor = tex.rgb; SHARED.sheenIntensity = tex.a; SHARED.sheenRoughness = uSheenRoughness; SHARED.outSheenColor = vec3(0.0); } void SPECULAR_LIGHT() { SHARED.outSheenColor += ...; } void POST_PROCESS() { COLOR_SUM = DIFFUSE + SPECULAR + EMISSIVE + SHARED.outSheenColor; }
注意: MAIN is called before others, and POST_PROCESS after all others, but that there is no guarantee for any other ordering for light processors.
The custom fragment shader code can freely access uniforms (such as,
CAMERA_DIRECTION
or
CAMERA_POSITION
), and varyings passed on from the custom vertex shader. Additionally, there are a number of built-in varyings available as special keywords. Some of these are optional in the sense that a vertex
MAIN
could calculate and pass on these on its own, but to reduce duplicated data fragment shaders can also rely on these built-ins instead. These built-ins are available in light processor functions and in the fragment MAIN.
VAR_WORLD_NORMAL
- Interpolated normal transformed by
NORMAL_MATRIX
.
VAR_WORLD_TANGENT
- Interpolated tangent transformed by
MODEL_MATRIX
.
VAR_WORLD_BINORMAL
- Interpolated binormal transformed by
MODEL_MATRIX
NORMAL
- Unlike
VAR_WORLD_NORMAL
, which is the interpolated normal as-is, this value is potentially adjusted for double-sidedness: when rendering with culling disabled, the normal will get inverted as necessary. Therefore lighting and other calculations are recommended to use
NORMAL
而不是
VAR_WORLD_NORMAL
in order behave correctly with all culling modes.
TANGENT
- Like
NORMAL
, this value is potentially adjusted for double-sidedness: when rendering with culling disabled, the tangent will get inverted as necessary.
BINORMAL
- Like
NORMAL
, this value is potentially adjusted for double-sidedness: when rendering with culling disabled, the binormal will get inverted as necessary.
VAR_WORLD_POSITION
- Interpolated world space vertex position (
(MODEL_MATRIX * vec4(VERTEX, 1.0)).xyz
)
VAR_COLOR
- The interpolated vertex color when colors are provided in the mesh.
vec4(1.0)
否则。
VIEW_VECTOR
- Points towards the camera. This is effectively the
CAMERA_POSITION - VAR_WORLD_POSITION
vector normalized.
FRAGCOORD
- Contains the window-relative coordinates of the current fragment.
FRAMEBUFFER_Y_UP
- The value is
1
when the Y axis points up in the coordinate system for framebuffers (textures), meaning
(0, 0)
is the bottom-left corner. The value is
-1
when the Y axis points down,
(0, 0)
being the top-left corner. Such differences in the underlying graphics APIs do not concern most custom materials. One notable exception is sampling
SCREEN_TEXTURE
with texture coordinates
not
基于
FRAGCOORD
. As the orientation of
SCREEN_TEXTURE
is tied to the underlying graphics API by nature, using texture coordinates from a mesh may need appropriate adjustments to the Y coordinate.
For example, the following fragment shader, suitable for Rectangle or Cube meshes, will display the opaque objects from the scene on the model:
VARYING vec2 texcoord; void MAIN() { vec2 screencoord = texcoord; if (FRAMEBUFFER_Y_UP < 0.0) // effectively: if not OpenGL screencoord.y = 1.0 - screencoord.y; BASE_COLOR = texture(SCREEN_TEXTURE, screencoord); }
When sampling textures other than
SCREEN_TEXTURE
and
DEPTH_TEXTURE
, or when
FRAGCOORD
is used to calculate the texture coordinate (which would be the typical use case for accessing the screen and depth textures), such an adjustment is not necessary.
NDC_Y_UP
- The value is
1
when the Y axis points up in normalized device coordinate space, and
-1
when the Y axis points down. Y pointing down is the case when rendering happens with Vulkan. Most materials do not need to be concerned by this, but being able to branch based on this can become useful in certain advanced use cases.
NEAR_CLIP_VALUE
- The value is
-1
for when the clipping plane range's starts at
-1
and goes to
1
. This is true when using OpenGL for rendering. For other rendering backends the value of this property will be
0
meaning the clipping plane range is
0
to
1
. This value is useful with certain techniques involving the
DEPTH_TEXTURE
For example, the following fragment shader demonstrates a technique for reconstructing the position of a value from the depth buffer to determine the distance from the current position being rendered. When used in combination with
INVERSE_PROJECTION_MATRIX
the value of depth needs to be in normalized device coordinates so it is important to make sure that the range of depth value reflects that. When the
NEAR_CLIP_VALUE
is
-1
then the depth value gets scaled to be between
-1
and
1
.
void MAIN() { vec2 screen_uv = FRAGCOORD.xy / vec2(textureSize(SCREEN_TEXTURE, 0)); float depth = texture(DEPTH_TEXTURE, screen_uv).r; if (NEAR_CLIP_VALUE < 0.0) // effectively: if opengl depth = depth * 2.0 - 1.0; vec4 unproject = INVERSE_PROJECTION_MATRIX * vec4(screen_uv, depth, 1.0); depth = (unproject.xyz / unproject.w).z; float viewVectorZ = (VIEW_MATRIX * vec4(VAR_WORLD_POSITION, 1.0)).z; depth = viewVectorZ - depth; BASE_COLOR = vec4(depth, depth, depth, 1.0); }
When doing instanced rendering, some of the keywords above do not apply. The following keywords are only available with instancing:
INSTANCE_MODEL_MATRIX
-> mat4, replacement for
MODEL_MATRIX
, including the instancing transformation.
INSTANCE_MODELVIEWPROJECTION_MATRIX
-> mat4, replacement for
MODELVIEWPROJECTION_MATRIX
, including the instancing transformation.
INSTANCE_COLOR
-> vec4, the instance color: to be combined with
COLOR
.
INSTANCE_DATA
-> vec4, instance custom data.
INSTANCE_INDEX
-> int, the instance number, and index into the instancing table.
The rendering pipeline can expose a number of textures to the custom material shaders with content from special render passes. This applies both to shaded and unshaded custom materials.
For example, a shader may want access to a depth texture that contains the depth buffer contents for the opaque objects in the scene. This is achieved by sampling
DEPTH_TEXTURE
. Such a texture is not normally generated, unless there is a real need for it. Therefore, the presence of the following keywords in the vertex or fragment shader also acts as a toggle for opting in to the - potentially expensive - passes for generating the texture in question. (of course, it could be that some of these become already enabled due to other settings, such as the ambient occlusion parameters in
SceneEnvironment
or due to a post-processing effect relying on the depth texture, in which case the textures in question are generated regardless of the custom material and so sampling these special textures in the material comes at no extra cost apart from the texture access itself)
SCREEN_TEXTURE
- When present, a texture (sampler2D) with the color buffer from a rendering pass containing the opaque objects in the scene is exposed to the shader under this name. This also implies that any object with a custom material where the shaders sample
SCREEN_TEXTURE
will be treated as if it had semi-transparency enabled on it, even when the object opacity is 1.0 and blending was not enabled on the CustomMaterial. This is because such an object cannot be part of the opaque rendering lists, because it itself depends on the rendering results of those objects and thus cannot be rendered in line together with those. Pixels that are not covered by opaque objects will be set to transparent (
vec4(0.0)
) in the texture. For example, a fragment shader could contain the following:
vec2 uv = FRAGCOORD.xy / vec2(textureSize(SCREEN_TEXTURE, 0)); vec2 displace = vec2(0.1); vec4 c = texture(SCREEN_TEXTURE, uv + displace);
Be aware that using
SCREEN_TEXTURE
requires appropriate, conscious design of the scene. Objects using such materials have to be positioned carefully, typically above all other objects that are expected to be visible in the texture. Objects that employ semi-transparency in some form are never part of the
SCREEN_TEXTURE
. Often
SCREEN_TEXTURE
will be used in combination with
BASE_COLOR
in
MAIN
. For example, the following custom fragment shader applies an emboss effect, while keeping fragments not touched by opaque objects transparent. This assumes that the object with the material is placed in the front, and that it has blending enabled.
void MAIN() { vec2 size = vec2(textureSize(SCREEN_TEXTURE, 0)); vec2 uv = FRAGCOORD.xy / size; // basic emboss effect vec2 d = vec2(1.0 / size.x, 1.0 / size.y); vec4 diff = texture(SCREEN_TEXTURE, uv + d) - texture(SCREEN_TEXTURE, uv - d); float c = (diff.x + diff.y + diff.z) + 0.5; float alpha = texture(SCREEN_TEXTURE, uv).a; BASE_COLOR = vec4(vec3(c), alpha); }
SCREEN_MIP_TEXTURE
- Identical to
SCREEN_TEXTURE
in most ways, the difference being that this texture has mipmaps generated. This can be an expensive feature performance-wise, depending on the screen size, and due to having to generate the mipmaps every time the scene is rendered. Therefore, prefer using
SCREEN_TEXTURE
always, unless a technique relying on the texture mip levels (e.g. using
textureLod
in the shader) is implemented by the custom material.
DEPTH_TEXTURE
- When present, a texture (sampler2D) with the (non-linearized) depth buffer contents is exposed to the shader under this name. Only opaque objects are included. For example, a fragment shader could contain the following:
ivec2 dtSize = textureSize(DEPTH_TEXTURE, 0); vec2 dtUV = (FRAGCOORD.xy) / vec2(dtSize); vec4 depthSample = texture(DEPTH_TEXTURE, dtUV); float zNear = CAMERA_PROPERTIES.x; float zFar = CAMERA_PROPERTIES.y; float zRange = zFar - zNear; float z_n = 2.0 * depthSample.r - 1.0; float d = 2.0 * zNear * zFar / (zFar + zNear - z_n * zRange); d /= zFar;
AO_TEXTURE
- When present and screen space ambient occlusion is enabled (meaning when the AO strength and distance are both non-zero) in
SceneEnvironment
, the SSAO texture (sampler2D) is exposed to the shader under this name. Sampling this texture can be useful in unshaded materials. Shaded materials have ambient occlusion support built in. This means that the ambient occlusion factor is taken into account automatically. Whereas in a fragment shader for an unshaded material one could write the following to achieve the same:
ivec2 aoSize = textureSize(AO_TEXTURE, 0); vec2 aoUV = (FRAGCOORD.xy) / vec2(aoSize); float aoFactor = texture(AO_TEXTURE, aoUV).x;
另请参阅 SceneEnvironment::tonemapMode , Qt Quick 3D - 自定义着色器范例 , Qt Quick 3D - 自定义材质范例 ,和 可编程材质、效果、几何图形和纹理数据 .
alwaysDirty : bool |
Specifies that the material state is always dirty, which indicates that the material needs to be refreshed every time it is used by the QtQuick3D .
destinationBlend : enumeration |
Specifies the destination blend factor. The default value is
CustomMaterial.NoBlend
.
常量 | 值 |
---|---|
CustomMaterial.NoBlend
|
|
CustomMaterial.Zero
|
|
CustomMaterial.One
|
|
CustomMaterial.SrcColor
|
|
CustomMaterial.OneMinusSrcColor
|
|
CustomMaterial.DstColor
|
|
CustomMaterial.OneMinusDstColor
|
|
CustomMaterial.SrcAlpha
|
|
CustomMaterial.OneMinusSrcAlpha
|
|
CustomMaterial.DstAlpha
|
|
CustomMaterial.OneMinusDstAlpha
|
|
CustomMaterial.ConstantColor
|
|
CustomMaterial.OneMinusConstantColor
|
|
CustomMaterial.ConstantAlpha
|
|
CustomMaterial.OneMinusConstantAlpha
|
|
CustomMaterial.SrcAlphaSaturate
|
fragmentShader : url |
Specfies the file with the snippet of custom fragment shader code.
The value is a URL and must either be a local file or use the qrc scheme to access files embedded via the Qt resource system. Relative file paths (without a scheme) are also accepted, in which case the file is treated as relative to the component (the
.qml
file).
另请参阅 vertexShader .
lineWidth : real |
This property determines the width of the lines rendered, when the geometry is using a primitive type of lines or line strips. The default value is 1.0. This property is not relevant when rendering other types of geometry, such as, triangle meshes.
警告: Line widths other than 1 may not be suported at run time, depending on the underlying graphics API. When that is the case, the request to change the width is ignored. For example, none of the following can be expected to support wide lines: Direct3D, Metal, OpenGL with core profile contexts.
注意: Unlike the line width, the value of which is part of the graphics pipeline object, the point size for geometries with a topology of points is controlled by the vertex shader (when supported), and has therefore no corresponding QML property.
shadingMode : enumeration |
Specifies the type of the material. The default value is Shaded.
常量 | 值 |
---|---|
CustomMaterial.Unshaded
|
|
CustomMaterial.Shaded
|
sourceBlend : enumeration |
Specifies the source blend factor. The default value is
CustomMaterial.NoBlend
.
常量 | 值 |
---|---|
CustomMaterial.NoBlend
|
|
CustomMaterial.Zero
|
|
CustomMaterial.One
|
|
CustomMaterial.SrcColor
|
|
CustomMaterial.OneMinusSrcColor
|
|
CustomMaterial.DstColor
|
|
CustomMaterial.OneMinusDstColor
|
|
CustomMaterial.SrcAlpha
|
|
CustomMaterial.OneMinusSrcAlpha
|
|
CustomMaterial.DstAlpha
|
|
CustomMaterial.OneMinusDstAlpha
|
|
CustomMaterial.ConstantColor
|
|
CustomMaterial.OneMinusConstantColor
|
|
CustomMaterial.ConstantAlpha
|
|
CustomMaterial.OneMinusConstantAlpha
|
|
CustomMaterial.SrcAlphaSaturate
|
vertexShader : url |
Specfies the file with the snippet of custom vertex shader code.
The value is a URL and must either be a local file or use the qrc scheme to access files embedded via the Qt resource system. Relative file paths (without a scheme) are also accepted, in which case the file is treated as relative to the component (the
.qml
file).
另请参阅 fragmentShader .