If we didn't find a gallium surface format that exactly matched the
glDrawPixels format/type combination, we used some other 32-bit packed
RGBA format and swizzled the whole image in the mesa texstore/format code.
That slow path can be avoided in some common cases by using the
pipe_samper_view's swizzle terms to do the swizzling at texture sampling
time instead.
For now, only GL_RGBA/ubyte and GL_BGRA/ubyte combinations are supported.
In the future other formats and types like GL_UNSIGNED_INT_8_8_8_8 could
be added.
---
src/mesa/state_tracker/st_cb_drawpixels.c | 73 +++++++++++++++++++++++++++----
1 file changed, 64 insertions(+), 9 deletions(-)
diff --git a/src/mesa/state_tracker/st_cb_drawpixels.c
b/src/mesa/state_tracker/st_cb_drawpixels.c
index 05f6e6b..a135761 100644
--- a/src/mesa/state_tracker/st_cb_drawpixels.c
+++ b/src/mesa/state_tracker/st_cb_drawpixels.c
@@ -395,15 +395,35 @@ make_texture(struct st_context *st,
* Note that the image is actually going to be upside down in
* the texture. We deal with that with texcoords.
*/
- success = _mesa_texstore(ctx, 2, /* dims */
- baseInternalFormat, /* baseInternalFormat */
- mformat, /* mesa_format */
- transfer->stride, /* dstRowStride, bytes */
- &dest, /* destSlices */
- width, height, 1, /* size */
- format, type, /* src format/type */
- pixels, /* data source */
- unpack);
+ if ((format == GL_RGBA || format == GL_BGRA)
+ && type == GL_UNSIGNED_BYTE) {
+ /* Use a memcpy-based texstore to avoid software pixel swizzling.
+ * We'll do the necessary swizzling with the pipe_sampler_view to
+ * give much better performance.
+ * XXX in the future, expand this to accomodate more format and
+ * type combinations.
+ */
+ _mesa_memcpy_texture(ctx, 2,
+ mformat, /* mesa_format */
+ transfer->stride, /* dstRowStride, bytes */
+ &dest, /* destSlices */
+ width, height, 1, /* size */
+ format, type, /* src format/type */
+ pixels, /* data source */
+ unpack);
+ success = GL_TRUE;
+ }
+ else {
+ success = _mesa_texstore(ctx, 2, /* dims */
+ baseInternalFormat, /* baseInternalFormat */
+ mformat, /* mesa_format */
+ transfer->stride, /* dstRowStride, bytes */
+ &dest, /* destSlices */
+ width, height, 1, /* size */
+ format, type, /* src format/type */
+ pixels, /* data source */
+ unpack);
+ }
/* unmap */
pipe_transfer_unmap(pipe, transfer);
@@ -958,6 +978,38 @@ clamp_size(struct pipe_context *pipe, GLsizei *width,
GLsizei *height,
/**
+ * Set the sampler view's swizzle terms. This is used to handle RGBA
+ * swizzling when the incoming image format isn't an exact match for
+ * the actual texture format. For example, if we have glDrawPixels(
+ * GL_RGBA, GL_UNSIGNED_BYTE) and we chose the texture format
+ * PIPE_FORMAT_B8G8R8A8 then we can do use the sampler view swizzle to
+ * avoid swizzling all the pixels in software in the texstore code.
+ */
+static void
+setup_sampler_swizzle(struct pipe_sampler_view *sv, GLenum format, GLenum type)
+{
+ if ((format == GL_RGBA || format == GL_BGRA) && type == GL_UNSIGNED_BYTE) {
+ const struct util_format_description *desc =
+ util_format_description(sv->texture->format);
+ /* Every gallium driver supports at least one 32-bit packed RGBA format.
+ * We must have chosen one for (GL_RGBA, GL_UNSIGNED_BYTE).
+ */
+ assert(desc->block.bits == 32);
+ /* use the format's swizzle to setup the sampler swizzle */
+ sv->swizzle_r = desc->swizzle[0];
+ sv->swizzle_g = desc->swizzle[1];
+ sv->swizzle_b = desc->swizzle[2];
+ sv->swizzle_a = desc->swizzle[3];
+ if (format == GL_BGRA) {
+ /* swap red/blue */
+ sv->swizzle_r = desc->swizzle[2];
+ sv->swizzle_b = desc->swizzle[0];
+ }
+ }
+}
+
+
+/**
* Called via ctx->Driver.DrawPixels()
*/
static void
@@ -1046,6 +1098,9 @@ st_DrawPixels(struct gl_context *ctx, GLint x, GLint y,
return;
}
+ /* Set up the sampler view's swizzle */
+ setup_sampler_swizzle(sv[0], format, type);
+
/* Create a second sampler view to read stencil. The stencil is
* written using the shader stencil export functionality.
*/
--
1.9.1
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