Projected Decal
A projected decal is a decal projected onto a surface by means of perspective projection. You can create an instance of the image projected onto a surface from a single point as a cone. These decals are of the same scale in spite of how far the surface they are projected onto is.
When the human eye views a scene, objects in the distance appear smaller than objects close by - this is known as perspective.
While orthographic projection ignores this effect to allow accurate measurements, perspective definition shows distant objects as smaller to provide additional realism.
See Also
- A DecalProj class to edit projected decals via UnigineScript.
- A set of samples located in the data/samples/decals/ directory:
- deferred_proj_00
- deferred_proj_01
Creating a Projected Decal
To create a projected decal, perform the following:
- On the Menu bar, choose Create -> Decal -> Projected.
- Place the decal on the existing surface (for the decal to be projected, the projection pyramid should intersect the surface) and specify the required settings:
Placement of the Projected Decal
Editing a Projected Decal
In the Decal tab you can adjust the following parameters of the projected decal:
Setting Bit Masks
A viewport bit-mask is available for the decal:
| Viewport | A viewport mask, specifying if the decal can be seen in the camera's viewport. |
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Projection Parameters
Parameters of the decal projection:
| Radius | The height of the projection pyramid along the Z axis, in units. |
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| Field of View | The field of view of the decal's projector, in degrees. |
| Aspect | The aspect ratio of the decal, in units. |
| ZNear | The value of the near clipping plane, ranging from 0 to 1. |
Life-time Parameters
Life-time and fade-out parameters:
| Life time | A time period during which the decal will be projected, in seconds. |
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| Fade time | A time period during which the decal will fade away (after its life time exceeds), in seconds. |
Visibility Parameters
Parameters controlling decal's visibility depending on the distance:
| Min visible | A minimum visibility distance, starting at which the decal begins to fade in and then becomes completely visible, in units. |
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| Fade | A minimum fade-in distance, across which the decal smoothly becomes visible due to the alpha fading. It is counted starting from the minimum visibility distance value, in units. |
| Max visible | A maximum visibility distance, starting at which the decal begins to fade out until becomes completely invisible, in units. |
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| Fade | A maximum fade-out distance, across which the decal smoothly becomes invisible due to the alpha fading. It is counted starting from the maximum visibility distance value, in units. |
Texture Coordinates Transformation
Decal's texture coordinates transformation (a texture atlas can also be used):
| ScaleX | A texture scale along the X-axis. For example, by the scale of 2 the texture is repeated twice on one decal. |
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| TranslateX | A texture offset along the X-axis. For example, by the offset of 0.5 along the X axis the texture is repositioned to the right (so that the edge of the texture is rendered in the center). |
| ScaleY | A texture scale along the Y-axis. |
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| TranslateY | A texture scale along the Y-axis. |
Setting a Material
A material selection:
| Material | A new material of the decal. |
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