src/mesa/drivers/dri/i965/brw_lower_texture_gradients.cpp

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