Brian Paul <bri...@vmware.com> writes: > Unless a fragment shader is active (very rare), all the fragments > emitted for a bitmap should have the same RGBA color. So the only two > possible outcomes of applying the alpha test to glBitmap is either the > bitmap is drawn normally (as if alpha test is disabled) or nothing is > drawn at all. I think we could test for this and either no-op the > glBitmap or draw the bitmap with the current code as-is. > > What do you think? > Yeah, that makes sense, fixed patch follows. Thank you for the review.
> -Brian
From ce79202f9bed892666539ef626ad49808c0428f9 Mon Sep 17 00:00:00 2001
From: Francisco Jerez <curroje...@riseup.net>
Date: Fri, 29 Oct 2010 21:20:34 +0200
Subject: [PATCH] meta: Handle bitmaps with alpha test enabled.
---
src/mesa/drivers/common/meta.c | 56 +++++++++++++++++++++++++++++++++------
1 files changed, 47 insertions(+), 9 deletions(-)
diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c
index 9615b52..8ebf5cf 100644
--- a/src/mesa/drivers/common/meta.c
+++ b/src/mesa/drivers/common/meta.c
@@ -104,6 +104,8 @@ struct save_state
/** META_ALPHA_TEST */
GLboolean AlphaEnabled;
+ GLenum AlphaFunc;
+ GLclampf AlphaRef;
/** META_BLEND */
GLbitfield BlendEnabled;
@@ -328,6 +330,8 @@ _mesa_meta_begin(struct gl_context *ctx, GLbitfield state)
if (state & META_ALPHA_TEST) {
save->AlphaEnabled = ctx->Color.AlphaEnabled;
+ save->AlphaFunc = ctx->Color.AlphaFunc;
+ save->AlphaRef = ctx->Color.AlphaRef;
if (ctx->Color.AlphaEnabled)
_mesa_set_enable(ctx, GL_ALPHA_TEST, GL_FALSE);
}
@@ -577,6 +581,7 @@ _mesa_meta_end(struct gl_context *ctx)
if (state & META_ALPHA_TEST) {
if (ctx->Color.AlphaEnabled != save->AlphaEnabled)
_mesa_set_enable(ctx, GL_ALPHA_TEST, save->AlphaEnabled);
+ _mesa_AlphaFunc(save->AlphaFunc, save->AlphaRef);
}
if (state & META_BLEND) {
@@ -1975,13 +1980,41 @@ _mesa_meta_DrawPixels(struct gl_context *ctx,
_mesa_meta_end(ctx);
}
+static GLboolean
+alpha_test_bitmap(struct gl_context *ctx)
+{
+ struct gl_colorbuffer_attrib *color = &ctx->Color;
+ GLenum func = (color->AlphaEnabled ? color->AlphaFunc : GL_ALWAYS);
+ GLubyte ref = FLOAT_TO_UBYTE(color->AlphaRef);
+ GLubyte alpha = FLOAT_TO_UBYTE(ctx->Current.RasterColor[ACOMP]);
+
+ switch (func) {
+ case GL_NEVER:
+ return GL_FALSE;
+ case GL_LESS:
+ return alpha < ref;
+ case GL_EQUAL:
+ return alpha == ref;
+ case GL_LEQUAL:
+ return alpha <= ref;
+ case GL_GREATER:
+ return alpha > ref;
+ case GL_NOTEQUAL:
+ return alpha != ref;
+ case GL_GEQUAL:
+ return alpha >= ref;
+ case GL_ALWAYS:
+ return GL_TRUE;
+ default:
+ assert(0);
+ return GL_FALSE;
+ }
+}
/**
- * Do glBitmap with a alpha texture quad. Use the alpha test to
- * cull the 'off' bits. If alpha test is already enabled, fall back
- * to swrast (should be a rare case).
- * A bitmap cache as in the gallium/mesa state tracker would
- * improve performance a lot.
+ * Do glBitmap with a alpha texture quad. Use the alpha test to cull
+ * the 'off' bits. A bitmap cache as in the gallium/mesa state
+ * tracker would improve performance a lot.
*/
void
_mesa_meta_Bitmap(struct gl_context *ctx,
@@ -1993,6 +2026,7 @@ _mesa_meta_Bitmap(struct gl_context *ctx,
struct temp_texture *tex = get_bitmap_temp_texture(ctx);
const GLenum texIntFormat = GL_ALPHA;
const struct gl_pixelstore_attrib unpackSave = *unpack;
+ GLubyte alpha = FLOAT_TO_UBYTE(ctx->Current.RasterColor[ACOMP]);
struct vertex {
GLfloat x, y, z, s, t, r, g, b, a;
};
@@ -2004,7 +2038,7 @@ _mesa_meta_Bitmap(struct gl_context *ctx,
* Check if swrast fallback is needed.
*/
if (ctx->_ImageTransferState ||
- ctx->Color.AlphaEnabled ||
+ ctx->FragmentProgram._Enabled ||
ctx->Fog.Enabled ||
ctx->Texture._EnabledUnits ||
width > tex->MaxSize ||
@@ -2013,6 +2047,9 @@ _mesa_meta_Bitmap(struct gl_context *ctx,
return;
}
+ if (!alpha_test_bitmap(ctx))
+ return;
+
/* Most GL state applies to glBitmap (like blending, stencil, etc),
* but a there's a few things we need to override:
*/
@@ -2100,15 +2137,16 @@ _mesa_meta_Bitmap(struct gl_context *ctx,
return;
}
- bitmap8 = (GLubyte *) calloc(1, width * height);
+ bitmap8 = (GLubyte *) malloc(width * height);
if (bitmap8) {
+ memset(bitmap8, ~alpha, width * height);
_mesa_expand_bitmap(width, height, &unpackSave, bitmap1,
- bitmap8, width, 0xff);
+ bitmap8, width, alpha);
_mesa_set_enable(ctx, tex->Target, GL_TRUE);
_mesa_set_enable(ctx, GL_ALPHA_TEST, GL_TRUE);
- _mesa_AlphaFunc(GL_GREATER, 0.0);
+ _mesa_AlphaFunc(GL_EQUAL, ctx->Current.RasterColor[ACOMP]);
setup_drawpix_texture(ctx, tex, newTex, texIntFormat, width, height,
GL_ALPHA, GL_UNSIGNED_BYTE, bitmap8);
--
1.6.4.4
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