From 5d5f0f349135786cdd76b6004f38b12e50d7f8f9 Mon Sep 17 00:00:00 2001 From: Paul Berry Date: Wed, 5 Sep 2012 16:07:16 -0700 Subject: [PATCH] mesa/msaa: Allow X and Y flips in multisampled blits. From the GL 4.3 spec, section 18.3.1 "Blitting Pixel Rectangles": If SAMPLE_BUFFERS for either the read framebuffer or draw framebuffer is greater than zero, no copy is performed and an INVALID_OPERATION error is generated if the dimensions of the source and destination rectangles provided to BlitFramebuffer are not identical, or if the formats of the read and draw framebuffers are not identical. It is not clear from the spec whether "dimensions" should mean both sign and magnitude, or just magnitude. Previously, Mesa interpreted "dimensions" as meaning both sign and magnitude, so any multisampled blit that attempted to flip the image in the X and/or Y direction would fail. However, Y flips are likely to be commonplace in OpenGL applications that have been ported from DirectX applications, as a result of the fact that DirectX and OpenGL differ in their orientation of the Y axis. Furthermore, at least one commercial driver (nVidia) permits Y filps, and L4D2 relies on them being permitted. So it seems prudent for Mesa to permit them. This patch changes Mesa to allow both X and Y flips, since there is no language in the spec to indicate that X and Y flips should be treated differently. NOTE: This is a candidate for stable release branches. Reviewed-by: Kenneth Graunke Reviewed-by: Anuj Phogat --- src/mesa/main/fbobject.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/mesa/main/fbobject.c b/src/mesa/main/fbobject.c index 59a5ec32d8a..abc9d83a648 100644 --- a/src/mesa/main/fbobject.c +++ b/src/mesa/main/fbobject.c @@ -2979,8 +2979,8 @@ _mesa_BlitFramebufferEXT(GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1, /* extra checks for multisample copies... */ if (readFb->Visual.samples > 0 || drawFb->Visual.samples > 0) { /* src and dest region sizes must be the same */ - if (srcX1 - srcX0 != dstX1 - dstX0 || - srcY1 - srcY0 != dstY1 - dstY0) { + if (abs(srcX1 - srcX0) != abs(dstX1 - dstX0) || + abs(srcY1 - srcY0) != abs(dstY1 - dstY0)) { _mesa_error(ctx, GL_INVALID_OPERATION, "glBlitFramebufferEXT(bad src/dst multisample region sizes)"); return; -- 2.11.0