This adds support for custom shaders for polys, and properly handles modulate in the case of large FVF and modulate FVF.
It also fixes poly vertex colors not being sent to OpenGL.
In small batches using hardware transform, vertices would be drawn in incorrect positions due to the item transform being applied twice - once in the transform uniform, and once from the transform passed as a vertex attribute.
This PR alters the shader to ignore uniform transforms when using large FVF.
Batching is mostly separated into a common template which can be used with multiple backends (GLES2 and GLES3 here). Only necessary specifics are in the backend files.
Batching is extended to cover more primitives.
When not using TEXTURE_RECT path, flips have to sent via another method to the shader, to ensure that normal maps are correctly adjusted for direction. This PR adds an extra vertex attribute, LIGHT_ANGLE.
For nvidia workarounds, where the shader still has access to the final transform and extra matrix, the LIGHT_ANGLE can be 0 (no adjustment), 180 degrees for a horizontal flip, and negative indicates a vertical flip.
For batching path, the LIGHT_ANGLE can be used to directly specify the light angle for normal mapping, even when the final transform and extra matrix have been baked into vertex positions, so the same shader can be used for both.
`ERROR: _display_error_with_code: CanvasShaderGLES3: Fragment Program Compilation Failed:
0:166(2): error: `return' with wrong type int, in function `map_ninepatch_axis' returning float` caused by #34704
In 2.1 and 3.0, light_vec could be modified for altering shadow_computations.
But it broke shadows when rotating light. shadow_vec would do the same, but without breaking
shadows in rotated lights if not used.
Add inverse light transformation to shadow vec, so it's not affected when rotating lights;
Added usage define for shadow vec.
For shadow vec working properly when rotating a light, it's needed to multiply it by light_matrix normalized. Added usage define in order to don't do that if shadow_vec not used.
Remove animation loop from ParticlesMaterial and move it to
SpatialMaterial for 3D particles and Particles2D for the 2D case.
Added animation to CPUParticles2D as well as the "Convert to
CPUParticles2D" to the PAarticles2D menu.
Custom instance transform was not taken into account for normal map
calculation. Also renamed `extra_matrix2` to `extra_matrix_instance` for
more clarity.
As of clang-format 6.0.1, putting the `/* clang-format off */` hint
around our "invalid" `[vertex]` and `[shader]` statements isn't enough
to prevent a bogus indent of the next comments and first valid statement,
so we need to enclose that first valid statement in the unformatted chunk.
