/**
* This uses a blit to copy the read buffer to a texture format which matches
* the format and type combo and then a fast read-back is done using memcpy.
* We can do arbitrary X/Y/Z/W/0/1 swizzling here as long as there is
* a format which matches the swizzling.
*
* If such a format isn't available, we fall back to _mesa_readpixels.
*
* NOTE: Some drivers use a blit to convert between tiled and linear
* texture layouts during texture uploads/downloads, so the blit
* we do here should be free in such cases.
*/
static void
st_readpixels(struct gl_context *ctx, GLint x, GLint y,
GLsizei width, GLsizei height,
GLenum format, GLenum type,
const struct gl_pixelstore_attrib *pack,
GLvoid *pixels)
{
struct st_context *st = st_context(ctx);
struct gl_renderbuffer *rb =
_mesa_get_read_renderbuffer_for_format(ctx, format);
struct st_renderbuffer *strb = st_renderbuffer(rb);
struct pipe_context *pipe = st->pipe;
struct pipe_screen *screen = pipe->screen;
struct pipe_resource *src;
struct pipe_resource *dst = NULL;
struct pipe_resource dst_templ;
enum pipe_format dst_format, src_format;
struct pipe_blit_info blit;
unsigned bind = PIPE_BIND_TRANSFER_READ;
struct pipe_transfer *tex_xfer;
ubyte *map = NULL;
/* Validate state (to be sure we have up-to-date framebuffer surfaces)
* and flush the bitmap cache prior to reading. */
st_validate_state(st);
st_flush_bitmap_cache(st);
if (!st->prefer_blit_based_texture_transfer) {
goto fallback;
}
/* This must be done after state validation. */
src = strb->texture;
/* XXX Fallback for depth-stencil formats due to an incomplete
* stencil blit implementation in some drivers. */
if (format == GL_DEPTH_STENCIL) {
goto fallback;
}
/* We are creating a texture of the size of the region being read back.
* Need to check for NPOT texture support. */
if (!screen->get_param(screen, PIPE_CAP_NPOT_TEXTURES) &&
(!util_is_power_of_two(width) ||
!util_is_power_of_two(height))) {
goto fallback;
}
/* If the base internal format and the texture format don't match, we have
* to use the slow path. */
if (rb->_BaseFormat !=
_mesa_get_format_base_format(rb->Format)) {
goto fallback;
}
/* See if the texture format already matches the format and type,
* in which case the memcpy-based fast path will likely be used and
* we don't have to blit. */
if (_mesa_format_matches_format_and_type(rb->Format, format,
type, pack->SwapBytes)) {
goto fallback;
}
if (_mesa_readpixels_needs_slow_path(ctx, format, type, GL_TRUE)) {
goto fallback;
}
/* Convert the source format to what is expected by ReadPixels
* and see if it's supported. */
src_format = util_format_linear(src->format);
src_format = util_format_luminance_to_red(src_format);
src_format = util_format_intensity_to_red(src_format);
if (!src_format ||
!screen->is_format_supported(screen, src_format, src->target,
src->nr_samples,
PIPE_BIND_SAMPLER_VIEW)) {
goto fallback;
}
if (format == GL_DEPTH_COMPONENT || format == GL_DEPTH_STENCIL)
bind |= PIPE_BIND_DEPTH_STENCIL;
else
bind |= PIPE_BIND_RENDER_TARGET;
/* Choose the destination format by finding the best match
* for the format+type combo. */
dst_format = st_choose_matching_format(screen, bind, format, type,
pack->SwapBytes);
if (dst_format == PIPE_FORMAT_NONE) {
goto fallback;
}
/* create the destination texture */
memset(&dst_templ, 0, sizeof(dst_templ));
dst_templ.target = PIPE_TEXTURE_2D;
dst_templ.format = dst_format;
dst_templ.bind = bind;
dst_templ.usage = PIPE_USAGE_STAGING;
st_gl_texture_dims_to_pipe_dims(GL_TEXTURE_2D, width, height, 1,
&dst_templ.width0, &dst_templ.height0,
&dst_templ.depth0, &dst_templ.array_size);
dst = screen->resource_create(screen, &dst_templ);
if (!dst) {
goto fallback;
}
memset(&blit, 0, sizeof(blit));
blit.src.resource = src;
blit.src.level = strb->surface->u.tex.level;
blit.src.format = src_format;
blit.dst.resource = dst;
blit.dst.level = 0;
blit.dst.format = dst->format;
blit.src.box.x = x;
blit.dst.box.x = 0;
blit.src.box.y = y;
blit.dst.box.y = 0;
blit.src.box.z = strb->surface->u.tex.first_layer;
blit.dst.box.z = 0;
blit.src.box.width = blit.dst.box.width = width;
blit.src.box.height = blit.dst.box.height = height;
blit.src.box.depth = blit.dst.box.depth = 1;
blit.mask = st_get_blit_mask(rb->_BaseFormat, format);
blit.filter = PIPE_TEX_FILTER_NEAREST;
blit.scissor_enable = FALSE;
if (st_fb_orientation(ctx->ReadBuffer) == Y_0_TOP) {
blit.src.box.y = rb->Height - blit.src.box.y;
blit.src.box.height = -blit.src.box.height;
}
/* blit */
st->pipe->blit(st->pipe, &blit);
/* map resources */
pixels = _mesa_map_pbo_dest(ctx, pack, pixels);
map = pipe_transfer_map_3d(pipe, dst, 0, PIPE_TRANSFER_READ,
0, 0, 0, width, height, 1, &tex_xfer);
if (!map) {
_mesa_unmap_pbo_dest(ctx, pack);
pipe_resource_reference(&dst, NULL);
goto fallback;
}
/* memcpy data into a user buffer */
{
const uint bytesPerRow = width * util_format_get_blocksize(dst_format);
GLuint row;
for (row = 0; row < (unsigned) height; row++) {
GLvoid *dest = _mesa_image_address3d(pack, pixels,
width, height, format,
type, 0, row, 0);
memcpy(dest, map, bytesPerRow);
map += tex_xfer->stride;
}
}
pipe_transfer_unmap(pipe, tex_xfer);
_mesa_unmap_pbo_dest(ctx, pack);
pipe_resource_reference(&dst, NULL);
return;
fallback:
_mesa_readpixels(ctx, x, y, width, height, format, type, pack, pixels);
}
/** Linearize and convert luminace/intensity to red. */
enum pipe_format si_simplify_cb_format(enum pipe_format format)
{
format = util_format_linear(format);
format = util_format_luminance_to_red(format);
return util_format_intensity_to_red(format);
}
