Improve 2D texture documentation.
PiperOrigin-RevId: 643347176 Change-Id: Ice83a723776092c762dac6e6bc440ef1b1d673b5
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@@ -1457,7 +1457,7 @@ still be specified here but this functionality is now deprecated and will be rem
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This attribute determines how the texture is represented and mapped to objects. It also determines which of the
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This attribute determines how the texture is represented and mapped to objects. It also determines which of the
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remaining attributes are relevant. The keywords have the following meaning:
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remaining attributes are relevant. The keywords have the following meaning:
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The **cube** type is the most common. It has the effect of shrink-wrapping a texture cube over an object. Apart from
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The **cube** type has the effect of shrink-wrapping a texture cube over an object. Apart from
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the adjustment provided by the texuniform attribute of :ref:`material <asset-material>`, the process is automatic.
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the adjustment provided by the texuniform attribute of :ref:`material <asset-material>`, the process is automatic.
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Internally the GPU constructs a ray from the center of the object to each pixel (or rather fragment), finds the
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Internally the GPU constructs a ray from the center of the object to each pixel (or rather fragment), finds the
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intersection of this ray with the cube surface (the cube and the object have the same center), and uses the
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intersection of this ray with the cube surface (the cube and the object have the same center), and uses the
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@@ -1480,15 +1480,13 @@ still be specified here but this functionality is now deprecated and will be rem
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a texture is referenced from a material applied to a regular object, the effect is equivalent to a cube map. Note
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a texture is referenced from a material applied to a regular object, the effect is equivalent to a cube map. Note
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however that the images suitable for skyboxes are rarely suitable for texturing objects.
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however that the images suitable for skyboxes are rarely suitable for texturing objects.
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The **2d** type may be the most familiar to users, however it is only suitable for planes and height fields. This is
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The **2d** type maps a 2D image to a 3D object using :ref:`texture coordinates<asset-mesh-texcoord>` (a.k.a UV
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because the texture coordinate generator is trying to map a 2D image to 3D space, and as a result there are entire
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coordinates). However, UV coordinates are only available for meshes. For primitive geoms, the texture is mapped to
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curves on the object surface that correspond to the same texture pixel. For a box geom for example, the two faces
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the object surface using the local XY coordinates of the geom, effectively projecting the texture along the Z axis.
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whose normals are aligned with the Z axis of the local frame appear normal, while the other four faces appear
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This sort of mapping is only suitable for planes and height fields, since their top surfaces always face the Z axis.
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stretched. For planes this is not an issue because the plane is always normal to the local Z axis. For height fields
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2d textures can be rectangular, unlike the sides of cube textures which must be square. The scaling can be controlled
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the sides enclosing the terrain map appear stretched, but in that case the effect is actually desirable. 2d textures
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with the texrepeat attribute of :ref:`material <asset-material>`. The data can be loaded from a single file or
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can be rectangular, unlike the sides of cube textures which must be square. The scaling can be controlled with the
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created procedurally.
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texrepeat attribute of :ref:`material <asset-material>`. The data can be loaded from a singlefile or created
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procedurally.
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.. _asset-texture-content_type:
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.. _asset-texture-content_type:
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