From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 11 Apr 2022 11:35:16 +0000 (+0300)
Subject: Preparatory refactoring of the texelFetch implementation
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=c585c065b7831eb6ae05e48edc36953d2534db2b

Preparatory refactoring of the texelFetch implementation
---

diff --git a/source/glsl/spirv.cpp b/source/glsl/spirv.cpp
index f8b36b26..61e59378 100644
--- a/source/glsl/spirv.cpp
+++ b/source/glsl/spirv.cpp
@@ -1371,17 +1371,25 @@ void SpirVGenerator::visit_builtin_texture(FunctionCall &call, const vector<Id>
 
 void SpirVGenerator::visit_builtin_texel_fetch(FunctionCall &call, const vector<Id> &argument_ids)
 {
-	if(argument_ids.size()!=3)
-		throw internal_error("invalid texelFetch call");
-
 	const ImageTypeDeclaration &image = dynamic_cast<const ImageTypeDeclaration &>(*call.arguments[0]->type);
 
-	r_expression_result_id = begin_expression(OP_IMAGE_FETCH, get_id(*call.type), 4);
+	Opcode opcode = OP_IMAGE_FETCH;
+
+	bool need_sample = image.multisample;
+	bool need_lod = !need_sample;
+
+	if(argument_ids.size()!=2U+need_sample+need_lod)
+		throw internal_error("invalid texture fetch call");
+
+	r_expression_result_id = begin_expression(opcode, get_id(*call.type), 2+(need_lod|need_sample)+need_lod+need_sample);
 	for(unsigned i=0; i<2; ++i)
 		writer.write(argument_ids[i]);
-	writer.write(image.multisample ? 0x40 : 0x02);  // Sample or Lod
-	writer.write(argument_ids.back());
-	end_expression(OP_IMAGE_FETCH);
+	if(need_lod || need_sample)
+	{
+		writer.write(need_lod*0x02 | need_sample*0x40);
+		writer.write(argument_ids.back());
+	}
+	end_expression(opcode);
 }
 
 void SpirVGenerator::visit_builtin_interpolate(FunctionCall &call, const vector<Id> &argument_ids)