diff options
| -rw-r--r-- | src/mesa/program/ir_to_mesa.cpp | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp index 1c674ea8756..4c8b097de6b 100644 --- a/src/mesa/program/ir_to_mesa.cpp +++ b/src/mesa/program/ir_to_mesa.cpp @@ -1237,8 +1237,19 @@ ir_to_mesa_visitor::visit(ir_expression *ir) ir->operands[1]->type->is_vector()) { src_reg temp = get_temp(glsl_type::vec4_type); emit(ir, OPCODE_SNE, dst_reg(temp), op[0], op[1]); + + /* After the dot-product, the value will be an integer on the + * range [0,4]. Zero becomes 1.0, and positive values become zero. + */ emit_dp(ir, result_dst, temp, temp, vector_elements); - emit(ir, OPCODE_SEQ, result_dst, result_src, src_reg_for_float(0.0)); + + /* Negating the result of the dot-product gives values on the range + * [-4, 0]. Zero becomes 1.0, and negative values become zero. This + * achieved using SGE. + */ + src_reg sge_src = result_src; + sge_src.negate = ~sge_src.negate; + emit(ir, OPCODE_SGE, result_dst, sge_src, src_reg_for_float(0.0)); } else { emit(ir, OPCODE_SEQ, result_dst, op[0], op[1]); } |