2 files changed, 70 insertions, 7 deletions
diff --git a/src/amberscript/parser.cc b/src/amberscript/parser.cc
index 953fc12..8157476 100644
--- a/src/amberscript/parser.cc
+++ b/src/amberscript/parser.cc
@@ -1894,16 +1894,21 @@ Result Parser::ParseRun() {
         count = token->AsUint32();
       }
     }
+
+    uint32_t vertex_count =
+        indexed ? pipeline->GetIndexBuffer()->ElementCount()
+                : pipeline->GetVertexBuffers()[0].buffer->ElementCount();
+
     // If we get here then we never set count, as if count was set it must
     // be > 0.
-    if (count == 0) {
-      count =
-          pipeline->GetVertexBuffers()[0].buffer->ElementCount() - start_idx;
-    }
+    if (count == 0)
+      count = vertex_count - start_idx;
 
-    if (start_idx + count >
-        pipeline->GetVertexBuffers()[0].buffer->ElementCount()) {
-      return Result("START_IDX plus COUNT exceeds vertex buffer data size");
+    if (start_idx + count > vertex_count) {
+      if (indexed)
+        return Result("START_IDX plus COUNT exceeds index buffer data size");
+      else
+        return Result("START_IDX plus COUNT exceeds vertex buffer data size");
     }
 
     auto cmd = MakeUnique<DrawArraysCommand>(pipeline, PipelineData{});
diff --git a/src/amberscript/parser_run_test.cc b/src/amberscript/parser_run_test.cc
index 4911414..4d2d69c 100644
--- a/src/amberscript/parser_run_test.cc
+++ b/src/amberscript/parser_run_test.cc
@@ -1404,6 +1404,64 @@ RUN my_pipeline DRAW_ARRAY AS TRIANGLE_LIST START_IDX 1 COUNT 9)";
             r.Error());
 }
 
+TEST_F(AmberScriptParserTest, RunDrawArraysIndexedStartIdxTooLarge) {
+  std::string in = R"(
+SHADER vertex my_shader PASSTHROUGH
+SHADER fragment my_fragment GLSL
+# GLSL Shader
+END
+BUFFER vtex_buf DATA_TYPE vec3<float> DATA
+1 2 3
+END
+BUFFER indices DATA_TYPE int32 DATA
+0 1 2 1 2 0
+END
+
+PIPELINE graphics my_pipeline
+  ATTACH my_shader
+  ATTACH my_fragment
+  VERTEX_DATA vtex_buf LOCATION 0
+  INDEX_DATA indices
+END
+
+RUN my_pipeline DRAW_ARRAY AS TRIANGLE_LIST INDEXED START_IDX 6 COUNT 1)";
+
+  Parser parser;
+  Result r = parser.Parse(in);
+  ASSERT_FALSE(r.IsSuccess());
+  EXPECT_EQ("20: START_IDX plus COUNT exceeds index buffer data size",
+            r.Error());
+}
+
+TEST_F(AmberScriptParserTest, RunDrawArraysIndexedCountTooLarge) {
+  std::string in = R"(
+SHADER vertex my_shader PASSTHROUGH
+SHADER fragment my_fragment GLSL
+# GLSL Shader
+END
+BUFFER vtex_buf DATA_TYPE vec3<float> DATA
+1 2 3
+END
+BUFFER indices DATA_TYPE int32 DATA
+0 1 2 1 2 0
+END
+
+PIPELINE graphics my_pipeline
+  ATTACH my_shader
+  ATTACH my_fragment
+  VERTEX_DATA vtex_buf LOCATION 0
+  INDEX_DATA indices
+END
+
+RUN my_pipeline DRAW_ARRAY AS TRIANGLE_LIST INDEXED START_IDX 1 COUNT 6)";
+
+  Parser parser;
+  Result r = parser.Parse(in);
+  ASSERT_FALSE(r.IsSuccess());
+  EXPECT_EQ("20: START_IDX plus COUNT exceeds index buffer data size",
+            r.Error());
+}
+
 TEST_F(AmberScriptParserTest, RunDrawArraysInvalidCountValueFormat) {
   std::string in = R"(
 SHADER vertex my_shader PASSTHROUGH