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 #include "program/prog_instruction.h"
  31 #include "brw_context.h"
  32
  33 using namespace ir_builder;
  34
  35 class lower_texture_grad_visitor : public ir_hierarchical_visitor {
  36 public:
  37    lower_texture_grad_visitor(bool has_sample_d_c)
  38       : has_sample_d_c(has_sample_d_c)
  39    {
  40       progress = false;
  41    }
  42
  43    ir_visitor_status visit_leave(ir_texture *ir);
  44
  45
  46    bool progress;
  47    bool has_sample_d_c;
  48
  49 private:
  50    void emit(ir_variable *, ir_rvalue *);
  51 };
  52
  53 /**
  54  * Emit a variable declaration and an assignment to initialize it.
  55  */
  56 void
  57 lower_texture_grad_visitor::emit(ir_variable *var, ir_rvalue *value)
  58 {
  59    base_ir->insert_before(var);
  60    base_ir->insert_before(assign(var, value));
  61 }
  62
  63 static const glsl_type *
  64 txs_type(const glsl_type *type)
  65 {
  66    unsigned dims;
  67    switch (type->sampler_dimensionality) {
  68    case GLSL_SAMPLER_DIM_1D:
  69       dims = 1;
  70       break;
  71    case GLSL_SAMPLER_DIM_2D:
  72    case GLSL_SAMPLER_DIM_RECT:
  73    case GLSL_SAMPLER_DIM_CUBE:
  74       dims = 2;
  75       break;
  76    case GLSL_SAMPLER_DIM_3D:
  77       dims = 3;
  78       break;
  79    default:
  80       unreachable("Should not get here: invalid sampler dimensionality");
  81    }
  82
  83    if (type->sampler_array)
  84       dims++;
  85
  86    return glsl_type::get_instance(GLSL_TYPE_INT, dims, 1);
  87 }
  88
  89 ir_visitor_status
  90 lower_texture_grad_visitor::visit_leave(ir_texture *ir)
  91 {
  92    /* Only lower textureGrad with shadow samplers */
  93    if (ir->op != ir_txd || !ir->shadow_comparitor)
  94       return visit_continue;
  95
  96    /* Lower textureGrad() with samplerCubeShadow even if we have the sample_d_c
  97     * message.  GLSL provides gradients for the 'r' coordinate.  Unfortunately:
  98     *
  99     * From the Ivybridge PRM, Volume 4, Part 1, sample_d message description:
 100     * "The r coordinate contains the faceid, and the r gradients are ignored
 101     *  by hardware."
 102     *
 103     * We likely need to do a similar treatment for samplerCube and
 104     * samplerCubeArray, but we have insufficient testing for that at the moment.
 105     */
 106    bool need_lowering = !has_sample_d_c ||
 107       ir->sampler->type->sampler_dimensionality == GLSL_SAMPLER_DIM_CUBE;
 108
 109    if (!need_lowering)
 110       return visit_continue;
 111
 112    void *mem_ctx = ralloc_parent(ir);
 113
 114    const glsl_type *grad_type = ir->lod_info.grad.dPdx->type;
 115
 116    /* Use textureSize() to get the width and height of LOD 0; swizzle away
 117     * the depth/number of array slices.
 118     */
 119    ir_texture *txs = new(mem_ctx) ir_texture(ir_txs);
 120    txs->set_sampler(ir->sampler->clone(mem_ctx, NULL),
 121                     txs_type(ir->sampler->type));
 122    txs->lod_info.lod = new(mem_ctx) ir_constant(0);
 123    ir_variable *size =
 124       new(mem_ctx) ir_variable(grad_type, "size", ir_var_temporary);
 125    if (ir->sampler->type->sampler_dimensionality == GLSL_SAMPLER_DIM_CUBE) {
 126       base_ir->insert_before(size);
 127       base_ir->insert_before(assign(size, expr(ir_unop_i2f, txs), WRITEMASK_XY));
 128       base_ir->insert_before(assign(size, new(mem_ctx) ir_constant(1.0f), WRITEMASK_Z));
 129    } else {
 130       emit(size, expr(ir_unop_i2f,
 131                       swizzle_for_size(txs, grad_type->vector_elements)));
 132    }
 133
 134    /* Scale the gradients by width and height.  Effectively, the incoming
 135     * gradients are s'(x,y), t'(x,y), and r'(x,y) from equation 3.19 in the
 136     * GL 3.0 spec; we want u'(x,y), which is w_t * s'(x,y).
 137     */
 138    ir_variable *dPdx =
 139       new(mem_ctx) ir_variable(grad_type, "dPdx", ir_var_temporary);
 140    emit(dPdx, mul(size, ir->lod_info.grad.dPdx));
 141
 142    ir_variable *dPdy =
 143       new(mem_ctx) ir_variable(grad_type, "dPdy", ir_var_temporary);
 144    emit(dPdy, mul(size, ir->lod_info.grad.dPdy));
 145
 146    /* Calculate rho from equation 3.20 of the GL 3.0 specification. */
 147    ir_rvalue *rho;
 148    if (dPdx->type->is_scalar()) {
 149       rho = expr(ir_binop_max, expr(ir_unop_abs, dPdx),
 150                                expr(ir_unop_abs, dPdy));
 151    } else {
 152       rho = expr(ir_binop_max, expr(ir_unop_sqrt, dot(dPdx, dPdx)),
 153                                expr(ir_unop_sqrt, dot(dPdy, dPdy)));
 154    }
 155
 156    /* lambda_base = log2(rho).  We're ignoring GL state biases for now. */
 157    ir->op = ir_txl;
 158    ir->lod_info.lod = expr(ir_unop_log2, rho);
 159
 160    progress = true;
 161    return visit_continue;
 162 }
 163
 164 extern "C" {
 165
 166 bool
 167 brw_lower_texture_gradients(struct brw_context *brw,
 168                             struct exec_list *instructions)
 169 {
 170    bool has_sample_d_c = brw->gen >= 8 || brw->is_haswell;
 171    lower_texture_grad_visitor v(has_sample_d_c);
 172
 173    visit_list_elements(&v, instructions);
 174
 175    return v.progress;
 176 }
 177
 178 }