Support binding the same vertex buffer to multiple locations (#936)

There's no need to restrict binding a vertex buffer to multiple locations. Now that we have OFFSET supported this has a real use case where the same buffer is used with different offsets.

1 files changed, 84 insertions, 0 deletions

diff --git a/tests/cases/vertex_data_two_locations.amber b/tests/cases/vertex_data_two_locations.amber
new file mode 100644
index 0000000..a9a4491
--- /dev/null
+++ b/tests/cases/vertex_data_two_locations.amber
@@ -0,0 +1,84 @@
+#!amber
+# Copyright 2021 The Amber Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+SHADER vertex vtex_shader GLSL
+#version 430
+
+layout(location = 0) in vec4 position;
+layout(location = 1) in vec4 vert_color0;
+layout(location = 2) in vec4 vert_color1;
+layout(location = 0) out vec4 frag_color;
+
+void main()
+{
+  gl_Position = position;
+  frag_color = vert_color0 + vert_color1;
+}
+END
+
+SHADER fragment frag_shader GLSL
+#version 430
+
+layout(location = 0) in vec4 frag_color;
+layout(location = 0) out vec4 final_color;
+
+void main()
+{
+  final_color = frag_color;
+}
+END
+
+BUFFER position_buf DATA_TYPE R8G8_SNORM DATA
+-128 -128
+ 127  127
+-128  127
+-128 -128
+ 127  127
+ 127 -128
+END
+
+BUFFER vert_color DATA_TYPE R8G8B8A8_UNORM DATA
+255   0   0   255
+255   0   0   255
+255   0   0   255
+255   0   0   255
+255   0   0   255
+255   0   0   255
+
+  0 255   0   255
+  0 255   0   255
+  0 255   0   255
+  0 255   0   255
+  0 255   0   255
+  0 255   0   255
+END
+
+BUFFER framebuffer FORMAT B8G8R8A8_UNORM
+
+PIPELINE graphics pipeline
+  ATTACH vtex_shader
+  ATTACH frag_shader
+
+  VERTEX_DATA position_buf LOCATION 0
+  VERTEX_DATA vert_color LOCATION 1
+  VERTEX_DATA vert_color LOCATION 2 OFFSET 24
+
+  BIND BUFFER framebuffer AS color LOCATION 0
+END
+
+CLEAR pipeline
+
+RUN pipeline DRAW_ARRAY AS TRIANGLE_LIST START_IDX 0 COUNT 6
+EXPECT framebuffer IDX 0 0 SIZE 250 250 EQ_RGBA 255 255 0 255