Home | History | Annotate | Download | only in glsl 
      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 (at) 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 = hieralloc_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 }
    100