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      1 /*
      2  * Copyright  2012 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 brw_lower_texture_gradients.cpp
     26  */
     27 
     28 #include "glsl/ir.h"
     29 #include "glsl/ir_builder.h"
     30 #include "program/prog_instruction.h"
     31 
     32 using namespace ir_builder;
     33 
     34 class lower_texture_grad_visitor : public ir_hierarchical_visitor {
     35 public:
     36    lower_texture_grad_visitor()
     37    {
     38       progress = false;
     39    }
     40 
     41    ir_visitor_status visit_leave(ir_texture *ir);
     42 
     43 
     44    bool progress;
     45 
     46 private:
     47    void emit(ir_variable *, ir_rvalue *);
     48 };
     49 
     50 /**
     51  * Emit a variable declaration and an assignment to initialize it.
     52  */
     53 void
     54 lower_texture_grad_visitor::emit(ir_variable *var, ir_rvalue *value)
     55 {
     56    base_ir->insert_before(var);
     57    base_ir->insert_before(assign(var, value));
     58 }
     59 
     60 static const glsl_type *
     61 txs_type(const glsl_type *type)
     62 {
     63    unsigned dims;
     64    switch (type->sampler_dimensionality) {
     65    case GLSL_SAMPLER_DIM_1D:
     66       dims = 1;
     67       break;
     68    case GLSL_SAMPLER_DIM_2D:
     69    case GLSL_SAMPLER_DIM_RECT:
     70    case GLSL_SAMPLER_DIM_CUBE:
     71       dims = 2;
     72       break;
     73    case GLSL_SAMPLER_DIM_3D:
     74       dims = 3;
     75       break;
     76    default:
     77       assert(!"Should not get here: invalid sampler dimensionality");
     78    }
     79 
     80    if (type->sampler_array)
     81       dims++;
     82 
     83    return glsl_type::get_instance(GLSL_TYPE_INT, dims, 1);
     84 }
     85 
     86 ir_visitor_status
     87 lower_texture_grad_visitor::visit_leave(ir_texture *ir)
     88 {
     89    /* Only lower textureGrad with shadow samplers */
     90    if (ir->op != ir_txd || !ir->shadow_comparitor)
     91       return visit_continue;
     92 
     93    void *mem_ctx = ralloc_parent(ir);
     94 
     95    const glsl_type *grad_type = ir->lod_info.grad.dPdx->type;
     96 
     97    /* Use textureSize() to get the width and height of LOD 0; swizzle away
     98     * the depth/number of array slices.
     99     */
    100    ir_texture *txs = new(mem_ctx) ir_texture(ir_txs);
    101    txs->set_sampler(ir->sampler->clone(mem_ctx, NULL),
    102 		    txs_type(ir->sampler->type));
    103    txs->lod_info.lod = new(mem_ctx) ir_constant(0);
    104    ir_variable *size =
    105       new(mem_ctx) ir_variable(grad_type, "size", ir_var_temporary);
    106    if (ir->sampler->type->sampler_dimensionality == GLSL_SAMPLER_DIM_CUBE) {
    107       base_ir->insert_before(size);
    108       base_ir->insert_before(assign(size, expr(ir_unop_i2f, txs), WRITEMASK_XY));
    109       base_ir->insert_before(assign(size, new(mem_ctx) ir_constant(1.0f), WRITEMASK_Z));
    110    } else {
    111       emit(size, expr(ir_unop_i2f,
    112                       swizzle_for_size(txs, grad_type->vector_elements)));
    113    }
    114 
    115    /* Scale the gradients by width and height.  Effectively, the incoming
    116     * gradients are s'(x,y), t'(x,y), and r'(x,y) from equation 3.19 in the
    117     * GL 3.0 spec; we want u'(x,y), which is w_t * s'(x,y).
    118     */
    119    ir_variable *dPdx =
    120       new(mem_ctx) ir_variable(grad_type, "dPdx", ir_var_temporary);
    121    emit(dPdx, mul(size, ir->lod_info.grad.dPdx));
    122 
    123    ir_variable *dPdy =
    124       new(mem_ctx) ir_variable(grad_type, "dPdy", ir_var_temporary);
    125    emit(dPdy, mul(size, ir->lod_info.grad.dPdy));
    126 
    127    /* Calculate rho from equation 3.20 of the GL 3.0 specification. */
    128    ir_rvalue *rho;
    129    if (dPdx->type->is_scalar()) {
    130       rho = expr(ir_binop_max, expr(ir_unop_abs, dPdx),
    131 			       expr(ir_unop_abs, dPdy));
    132    } else {
    133       rho = expr(ir_binop_max, expr(ir_unop_sqrt, dot(dPdx, dPdx)),
    134 			       expr(ir_unop_sqrt, dot(dPdy, dPdy)));
    135    }
    136 
    137    /* lambda_base = log2(rho).  We're ignoring GL state biases for now. */
    138    ir->op = ir_txl;
    139    ir->lod_info.lod = expr(ir_unop_log2, rho);
    140 
    141    progress = true;
    142    return visit_continue;
    143 }
    144 
    145 extern "C" {
    146 
    147 bool
    148 brw_lower_texture_gradients(struct exec_list *instructions)
    149 {
    150    lower_texture_grad_visitor v;
    151 
    152    visit_list_elements(&v, instructions);
    153 
    154    return v.progress;
    155 }
    156 
    157 }
    158