diff options
| -rw-r--r-- | src/mesa/state_tracker/st_cb_bitmap.c | 49 |
1 files changed, 20 insertions, 29 deletions
diff --git a/src/mesa/state_tracker/st_cb_bitmap.c b/src/mesa/state_tracker/st_cb_bitmap.c index 8feae73fe00..975a55d6dc0 100644 --- a/src/mesa/state_tracker/st_cb_bitmap.c +++ b/src/mesa/state_tracker/st_cb_bitmap.c @@ -60,6 +60,19 @@ /** + * glBitmaps are drawn as textured quads. The user's bitmap pattern + * is stored in a texture image. An alpha8 texture format is used. + * The fragment shader samples a bit (texel) from the texture, then + * discards the fragment if the bit is off. + * + * Note that we actually store the inverse image of the bitmap to + * simplify the fragment program. An "on" bit gets stored as texel=0x0 + * and an "off" bit is stored as texel=0xff. Then we kill the + * fragment if the negated texel value is less than zero. + */ + + +/** * The bitmap cache attempts to accumulate multiple glBitmap calls in a * buffer which is then rendered en mass upon a flush, state change, etc. * A wide, short buffer is used to target the common case of a series @@ -102,7 +115,7 @@ make_bitmap_fragment_program(GLcontext *ctx) if (!p) return NULL; - p->NumInstructions = 5; + p->NumInstructions = 3; p->Instructions = _mesa_alloc_instructions(p->NumInstructions); if (!p->Instructions) { @@ -121,33 +134,11 @@ make_bitmap_fragment_program(GLcontext *ctx) p->Instructions[ic].TexSrcTarget = TEXTURE_2D_INDEX; ic++; - /* SWZ tmp0.x, tmp0.x, 1111; # tmp0.x = 1.0 */ - p->Instructions[ic].Opcode = OPCODE_SWZ; - p->Instructions[ic].DstReg.File = PROGRAM_TEMPORARY; - p->Instructions[ic].DstReg.Index = 0; - p->Instructions[ic].DstReg.WriteMask = WRITEMASK_X; - p->Instructions[ic].SrcReg[0].File = PROGRAM_TEMPORARY; - p->Instructions[ic].SrcReg[0].Index = 0; - p->Instructions[ic].SrcReg[0].Swizzle - = MAKE_SWIZZLE4(SWIZZLE_ONE, SWIZZLE_ONE, SWIZZLE_ONE, SWIZZLE_ONE ); - ic++; - - /* SUB tmp0, tmp0.wwww, tmp0.xxxx; # tmp0.w -= 1 */ - p->Instructions[ic].Opcode = OPCODE_SUB; - p->Instructions[ic].DstReg.File = PROGRAM_TEMPORARY; - p->Instructions[ic].DstReg.Index = 0; - p->Instructions[ic].SrcReg[0].File = PROGRAM_TEMPORARY; - p->Instructions[ic].SrcReg[0].Index = 0; - p->Instructions[ic].SrcReg[0].Swizzle = SWIZZLE_WWWW; - p->Instructions[ic].SrcReg[1].File = PROGRAM_TEMPORARY; - p->Instructions[ic].SrcReg[1].Index = 0; - p->Instructions[ic].SrcReg[1].Swizzle = SWIZZLE_XXXX; /* 1.0 */ - ic++; - - /* KIL if tmp0 < 0 */ + /* KIL if -tmp0 < 0 # texel=0 -> keep / texel=0 -> discard */ p->Instructions[ic].Opcode = OPCODE_KIL; p->Instructions[ic].SrcReg[0].File = PROGRAM_TEMPORARY; p->Instructions[ic].SrcReg[0].Index = 0; + p->Instructions[ic].SrcReg[0].NegateBase = NEGATE_XYZW; ic++; /* END; */ @@ -289,7 +280,7 @@ make_bitmap_texture(GLcontext *ctx, GLsizei width, GLsizei height, for (col = 0; col < width; col++) { /* set texel to 255 if bit is set */ - destRow[comp] = (*src & mask) ? 255 : 0; + destRow[comp] = (*src & mask) ? 0x0 : 0xff; destRow += cpp; if (mask == 128U) { @@ -311,7 +302,7 @@ make_bitmap_texture(GLcontext *ctx, GLsizei width, GLsizei height, for (col = 0; col < width; col++) { /* set texel to 255 if bit is set */ - destRow[comp] =(*src & mask) ? 255 : 0; + destRow[comp] =(*src & mask) ? 0x0 : 0xff; destRow += cpp; if (mask == 1U) { @@ -505,7 +496,7 @@ draw_bitmap_quad(GLcontext *ctx, GLint x, GLint y, GLfloat z, static void reset_cache(struct st_context *st) { - memset(st->bitmap.cache->buffer, 0, sizeof(st->bitmap.cache->buffer)); + memset(st->bitmap.cache->buffer, 0xff, sizeof(st->bitmap.cache->buffer)); st->bitmap.cache->empty = GL_TRUE; st->bitmap.cache->xmin = 1000000; @@ -642,7 +633,7 @@ accum_bitmap(struct st_context *st, /* XXX try to combine this code with code in make_bitmap_texture() */ #define SET_PIXEL(COL, ROW) \ - cache->buffer[py + (ROW)][px + (COL)] = 0xff; + cache->buffer[py + (ROW)][px + (COL)] = 0x0; for (row = 0; row < height; row++) { const GLubyte *src = (const GLubyte *) _mesa_image_address2d(unpack, |