Also, all the images cannot use the shareable backends before the
game starts, but it is expected that read-only images will use
shareable backends later.
Fixes#879
CopyPixels is basically Pixels and ReplacePixels, but executed
lazily while Pixels reads pixels from GPU immediately. Thanks to
this, restorable.Image no longer need to keep pixel data if not
needed.
Before introducing Fill, filling an image with a solid color was
implemented by ReplacePixels. When an offscreen image is used, the
offscreen image is not fully cleared or filled with a color and
out of (0,0)-(width,height) region. This causes a glitch thin line
on mobile platforms.
This change adds (*shareable.Image).Fill to fill the whole
framebuffer region of the image.
ReplacePixels on a part of image might invalidate the other part of
the image on MacBook Pro 2013, especially when the other part is
rendered by DrawImage.
Fixes#593#758
Now ReplacePixels command is called only when necessary.
This also ensures that DrawImage must be called after ReplacePixels
is called since there is a potential problem that rendering images
on a texture without initializing by replacing pixels might cause
problems (escpecially on Metal. Perhaps #593 might be related).
DrawTriangles is expensive and slow because of massive memory
allocation and garbage collection costs. This patch moves from ~47TPS
on my laptop (with ~24k triangles) to 60TPS. The first part
is just allocating the right size of vertex buffer up front; that
got to about 55TPS. The second part replaces the frequent
allocations of []float32 in Vertex() calls with writing the
desired values into a provided destination slice.
Time spent in drawing triangles for 1,000 frames:
13.07s baseline
11.09s preallocate whole buffer to avoid resizing
6.13s use new PutVertex function
This might need some cleanup, but I think it's good evidence that
the design change is viable.
