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      1 /**************************************************************************
      2  *
      3  * Copyright 2009 VMware, Inc.
      4  * All Rights Reserved.
      5  *
      6  * Permission is hereby granted, free of charge, to any person obtaining a
      7  * copy of this software and associated documentation files (the
      8  * "Software"), to deal in the Software without restriction, including
      9  * without limitation the rights to use, copy, modify, merge, publish,
     10  * distribute, sub license, and/or sell copies of the Software, and to
     11  * permit persons to whom the Software is furnished to do so, subject to
     12  * the following conditions:
     13  *
     14  * The above copyright notice and this permission notice (including the
     15  * next paragraph) shall be included in all copies or substantial portions
     16  * of the Software.
     17  *
     18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
     19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
     21  * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
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     23  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
     24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     25  *
     26  **************************************************************************/
     27 
     28 /**
     29  * Alpha testing to LLVM IR translation.
     30  *
     31  * @author Jose Fonseca <jfonseca (at) vmware.com>
     32  */
     33 
     34 #include "pipe/p_state.h"
     35 #include "util/u_format.h"
     36 
     37 #include "gallivm/lp_bld_type.h"
     38 #include "gallivm/lp_bld_const.h"
     39 #include "gallivm/lp_bld_arit.h"
     40 #include "gallivm/lp_bld_conv.h"
     41 #include "gallivm/lp_bld_logic.h"
     42 #include "gallivm/lp_bld_flow.h"
     43 #include "gallivm/lp_bld_debug.h"
     44 
     45 #include "lp_bld_alpha.h"
     46 
     47 
     48 void
     49 lp_build_alpha_test(struct gallivm_state *gallivm,
     50                     unsigned func,
     51                     struct lp_type type,
     52                     const struct util_format_description *cbuf_format_desc,
     53                     struct lp_build_mask_context *mask,
     54                     LLVMValueRef alpha,
     55                     LLVMValueRef ref,
     56                     boolean do_branch)
     57 {
     58    struct lp_build_context bld;
     59    LLVMValueRef test;
     60 
     61    lp_build_context_init(&bld, gallivm, type);
     62 
     63    /*
     64     * Alpha testing needs to be done in the color buffer precision.
     65     *
     66     * TODO: Ideally, instead of duplicating the color conversion code, we would do
     67     * alpha testing after converting the output colors, but that's not very
     68     * convenient, because it needs to be done before depth testing.  Hopefully
     69     * LLVM will detect and remove the duplicate expression.
     70     *
     71     * FIXME: This should be generalized to formats other than rgba8 variants.
     72     */
     73    if (type.floating &&
     74        util_format_is_rgba8_variant(cbuf_format_desc)) {
     75       const unsigned dst_width = 8;
     76 
     77       alpha = lp_build_clamp(&bld, alpha, bld.zero, bld.one);
     78       ref   = lp_build_clamp(&bld, ref,   bld.zero, bld.one);
     79 
     80       alpha = lp_build_clamped_float_to_unsigned_norm(gallivm, type, dst_width, alpha);
     81       ref   = lp_build_clamped_float_to_unsigned_norm(gallivm, type, dst_width, ref);
     82 
     83       type.floating = 0;
     84       lp_build_context_init(&bld, gallivm, type);
     85    }
     86 
     87    test = lp_build_cmp(&bld, func, alpha, ref);
     88 
     89    lp_build_name(test, "alpha_mask");
     90 
     91    lp_build_mask_update(mask, test);
     92 
     93    if (do_branch)
     94       lp_build_mask_check(mask);
     95 }
     96