In Unity, to ensure that your quad always faces the camera in addition to applying other transformations specified by the matrix, you need to modify the matrix transformation in your code. This is usually achieved by incorporating a “billboarding” effect, where the object always faces the camera.
The Graphics.DrawMesh method you’re using draws a mesh with a given transformation matrix. To modify this so the quad faces the camera, you’ll want to include a rotation matrix that aligns the quad with the camera’s view direction.
Here’s how you can do this:
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Calculate the LookAt Rotation Matrix: This matrix will orient the quad so that it faces the camera. You can use Quaternion.LookRotation for this. You need to provide the direction towards the camera as the first argument and the up direction as the second argument.
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Combine Matrices: Multiply the LookAt rotation matrix with your existing transformation matrix. This ensures that the quad faces the camera while still applying the original transformations.
The code would look something like this:
for (int i = 0; i < LinearMeshes.Length; i++)
// Calculate the direction towards the camera
Vector3 toCamera = Camera.main.transform.position - transform.position;
// Create a rotation that looks in the direction of the camera
Quaternion lookAtRotation = Quaternion.LookRotation(toCamera, Vector3.up);
// Combine the lookAtRotation with your existing matrix
Matrix4x4 combinedMatrix = transform.localToWorldMatrix * lookAtRotation * (Matrix4x4)matrices[i];
// Draw the mesh with the combined matrix
Graphics.DrawMesh(LinearMeshes[i], combinedMatrix, lineMat, 0);
In this code, Camera.main.transform.position gets the position of the main camera, and transform.position is the position of your object. The lookAtRotation aligns the quad to face towards the camera. Then, this rotation is combined with your existing transformation matrices.
Remember, if your camera is moving, you’ll need to recalculate this every frame to ensure the quad always faces the camera.