GPU: Add workaround for faulty default attrib values on some drivers

On some drivers, the default values is not respected correctly.

To workaround this we create a small VBO that contains only 1 vec4 worth of
data and just bind it using glBindVertexBuffer to ensure 0 stride.

This fixes T75069 Instances not rendered correctly by workbench.

1 files changed, 3 insertions, 0 deletions

diff --git a/source/blender/gpu/intern/gpu_shader_interface.c b/source/blender/gpu/intern/gpu_shader_interface.c
index f23a0a438d6..349a7217456 100644
--- a/source/blender/gpu/intern/gpu_shader_interface.c
+++ b/source/blender/gpu/intern/gpu_shader_interface.c
@@ -236,6 +236,7 @@ GPUShaderInterface *GPU_shaderinterface_create(int32_t program)
   shaderface->name_buffer = MEM_mallocN(name_buffer_len, "name_buffer");
 
   /* Attributes */
+  shaderface->enabled_attrib_mask = 0;
   for (uint32_t i = 0; i < attr_len; i++) {
     GPUShaderInput *input = MEM_mallocN(sizeof(GPUShaderInput), "GPUShaderInput Attr");
     GLsizei remaining_buffer = name_buffer_len - shaderface->name_buffer_offset;
@@ -255,6 +256,8 @@ GPUShaderInterface *GPU_shaderinterface_create(int32_t program)
 
     input->location = glGetAttribLocation(program, name);
 
+    shaderface->enabled_attrib_mask |= (1 << input->location);
+
     set_input_name(shaderface, input, name, name_len);
 
     shader_input_to_bucket(input, shaderface->attr_buckets);