Attachment 60068 Details for Bug 48545 – add another fast path for glReadPixels

[patch] add another fast path for glReadPixels

readpix-swizzle2.patch (text/plain), 2.80 KB, created by Brian Paul on 2012-04-16 08:53:14 UTC

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Creator: Brian Paul

Created: 2012-04-16 08:53:14 UTC

Size: 2.80 KB

patch

obsolete

>diff --git a/src/mesa/main/readpix.c b/src/mesa/main/readpix.c
>index 4918549..0c52582 100644
>--- a/src/mesa/main/readpix.c
>+++ b/src/mesa/main/readpix.c
>@@ -208,6 +208,11 @@ read_stencil_pixels( struct gl_context *ctx,
>    ctx->Driver.UnmapRenderbuffer(ctx, rb);
> }
> 
>+
>+/**
>+ * Try to do glReadPixels of RGBA data using a simple memcpy or swizzle.
>+ * \return GL_TRUE if successful, GL_FALSE otherwise (use the slow path)
>+ */
> static GLboolean
> fast_read_rgba_pixels_memcpy( struct gl_context *ctx,
> 			      GLint x, GLint y,
>@@ -220,9 +225,23 @@ fast_read_rgba_pixels_memcpy( struct gl_context *ctx,
>    struct gl_renderbuffer *rb = ctx->ReadBuffer->_ColorReadBuffer;
>    GLubyte *dst, *map;
>    int dstStride, stride, j, texelBytes;
>-
>-   if (!_mesa_format_matches_format_and_type(rb->Format, format, type,
>-                                             ctx->Pack.SwapBytes))
>+   GLboolean swizzle_rb = GL_FALSE, copy_xrgb = GL_FALSE;
>+
>+   /* XXX we could check for other swizzle cases here */
>+   if (rb->Format == MESA_FORMAT_RGBA8888_REV &&
>+       format == GL_BGRA &&
>+       type == GL_UNSIGNED_INT_8_8_8_8_REV &&
>+       !ctx->Pack.SwapBytes) {
>+      swizzle_rb = GL_TRUE;
>+   }
>+   else if (rb->Format == MESA_FORMAT_XRGB8888_REV &&
>+       format == GL_BGRA &&
>+       type == GL_UNSIGNED_INT_8_8_8_8_REV &&
>+       !ctx->Pack.SwapBytes) {
>+      copy_xrgb = GL_TRUE;
>+   }
>+   else if (!_mesa_format_matches_format_and_type(rb->Format, format, type,
>+                                                  ctx->Pack.SwapBytes))
>       return GL_FALSE;
> 
>    /* If the format is unsigned normalized then we can ignore clamping
>@@ -247,10 +266,38 @@ fast_read_rgba_pixels_memcpy( struct gl_context *ctx,
>    }
> 
>    texelBytes = _mesa_get_format_bytes(rb->Format);
>-   for (j = 0; j < height; j++) {
>-      memcpy(dst, map, width * texelBytes);
>-      dst += dstStride;
>-      map += stride;
>+
>+   if (swizzle_rb) {
>+      /* swap R/B */
>+      for (j = 0; j < height; j++) {
>+         int i;
>+         for (i = 0; i < width; i++) {
>+            dst[i*4+0] = map[i*4+2];
>+            dst[i*4+1] = map[i*4+1];
>+            dst[i*4+2] = map[i*4+0];
>+            dst[i*4+3] = map[i*4+3];
>+         }
>+         dst += dstStride;
>+         map += stride;
>+      }
>+   } else if (copy_xrgb) {
>+      /* convert xrgb -> argb */
>+      for (j = 0; j < height; j++) {
>+         GLuint *dst4 = (GLuint *) dst, *map4 = (GLuint *) map;
>+         int i;
>+         for (i = 0; i < width; i++) {
>+            dst4[i] = map4[i] | 0xff000000;  /* set A=0xff */
>+         }
>+         dst += dstStride;
>+         map += stride;
>+      }
>+   } else {
>+      /* just memcpy */
>+      for (j = 0; j < height; j++) {
>+         memcpy(dst, map, width * texelBytes);
>+         dst += dstStride;
>+         map += stride;
>+      }
>    }
> 
>    ctx->Driver.UnmapRenderbuffer(ctx, rb);

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