Scaling in WebGL is a geometric transformation used to change the size of an object. It does not alter the object's shape but scales it along each axis by a specified scale factor. For example, if an object has a scale factor of 2 on the x-axis, all points along the x-axis are multiplied by 2, doubling the object's size in the x-direction.
Implementing scaling in WebGL typically involves modifying or setting the model transformation matrix. The model transformation matrix allows convenient control over object translation, rotation, and scaling. Scaling can be achieved by constructing a scaling matrix and multiplying it with the original model matrix to obtain a new model matrix containing the scaled transformation information.
For instance, to scale an object uniformly by a factor of 2 in all directions, the following scaling matrix can be used:
[ 2.0, 0.0, 0.0, 0.0, 0.0, 2.0, 0.0, 0.0, 0.0, 0.0, 2.0, 0.0, 0.0, 0.0, 0.0, 1.0 ]
This matrix is multiplied with the object's existing model matrix, and the resulting matrix is used to render the transformed object.
Additionally, non-uniform scaling can be implemented, such as scaling only along the x-axis by setting the x-axis scale factor while setting y and z to 1.
A specific application of scaling is adjusting object sizes in 3D games or visualization applications to meet different visual effect requirements or physical space constraints. For instance, in a virtual reality game, certain objects may need to be adjusted in size based on the game scene's requirements to appear larger or smaller. By adjusting the scaling matrix parameters, this can be easily achieved without modifying the object's vertex data.