src/glsl/lower_texture_projection.cpp

   1 /*
   2  * Copyright © 2010 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 /**
  25  * \file lower_texture_projection.cpp
  26  *
  27  * IR lower pass to perform the division of texture coordinates by the texture
  28  * projector if present.
  29  *
  30  * Many GPUs have a texture sampling opcode that takes the projector
  31  * and does the divide internally, thus the presence of the projector
  32  * in the IR.  For GPUs that don't, this saves the driver needing the
  33  * logic for handling the divide.
  34  *
  35  * \author Eric Anholt <eric@anholt.net>
  36  */
  37
  38 #include "ir.h"
  39
  40 class lower_texture_projection_visitor : public ir_hierarchical_visitor {
  41 public:
  42    lower_texture_projection_visitor()
  43    {
  44       progress = false;
  45    }
  46
  47    ir_visitor_status visit_leave(ir_texture *ir);
  48
  49    bool progress;
  50 };
  51
  52 ir_visitor_status
  53 lower_texture_projection_visitor::visit_leave(ir_texture *ir)
  54 {
  55    if (!ir->projector)
  56       return visit_continue;
  57
  58    void *mem_ctx = ralloc_parent(ir);
  59
  60    ir_variable *var = new(mem_ctx) ir_variable(ir->projector->type,
  61                                                "projector", ir_var_auto);
  62    base_ir->insert_before(var);
  63    ir_dereference *deref = new(mem_ctx) ir_dereference_variable(var);
  64    ir_expression *expr = new(mem_ctx) ir_expression(ir_unop_rcp,
  65                                                     ir->projector->type,
  66                                                     ir->projector,
  67                                                     NULL);
  68    ir_assignment *assign = new(mem_ctx) ir_assignment(deref, expr, NULL);
  69    base_ir->insert_before(assign);
  70
  71    deref = new(mem_ctx) ir_dereference_variable(var);
  72    ir->coordinate = new(mem_ctx) ir_expression(ir_binop_mul,
  73                                                ir->coordinate->type,
  74                                                ir->coordinate,
  75                                                deref);
  76
  77    if (ir->shadow_comparitor) {
  78       deref = new(mem_ctx) ir_dereference_variable(var);
  79       ir->shadow_comparitor = new(mem_ctx) ir_expression(ir_binop_mul,
  80                                                   ir->shadow_comparitor->type,
  81                                                   ir->shadow_comparitor,
  82                                                   deref);
  83    }
  84
  85    ir->projector = NULL;
  86
  87    progress = true;
  88    return visit_continue;
  89 }
  90
  91 bool
  92 do_lower_texture_projection(exec_list *instructions)
  93 {
  94    lower_texture_projection_visitor v;
  95
  96    visit_list_elements(&v, instructions);
  97
  98    return v.progress;
  99 }