Uniforms: Support buffer protocol (#2463)

Author: einarf

arcade/gl/uniform.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import struct
 from ctypes import POINTER, cast
 
 from pyglet import gl
@@ -274,12 +275,18 @@ def _create_setter_func(
         is_matrix,
     ):
         """Create setters for OpenGL data."""
+        # Matrix uniforms
         if is_matrix:
             if ctx._ext_separate_shader_objects_enabled:
 
                 def setter_func(value):  # type: ignore #conditional function variants must have identical signature
                     """Set OpenGL matrix uniform data."""
-                    c_array[:] = value
+                    try:
+                        # FIXME: Configure the struct format on the uniform to support
+                        #        other types than float
+                        c_array[:] = struct.unpack(f"{length}f", value)
+                    except Exception:
+                        c_array[:] = value
                     gl_program_setter(program_id, location, array_length, gl.GL_FALSE, ptr)
 
             else:
@@ -290,6 +297,7 @@ def setter_func(value):  # type: ignore #conditional function variants must have
                     gl.glUseProgram(program_id)
                     gl_setter(location, array_length, gl.GL_FALSE, ptr)
 
+        # Single value uniforms
         elif length == 1 and count == 1:
             if ctx._ext_separate_shader_objects_enabled:
 
@@ -306,12 +314,20 @@ def setter_func(value):  # type: ignore #conditional function variants must have
                     gl.glUseProgram(program_id)
                     gl_setter(location, array_length, ptr)
 
+        # Uniforms types with multiple components
         elif length > 1 and count == 1:
             if ctx._ext_separate_shader_objects_enabled:
 
                 def setter_func(values):  # type: ignore #conditional function variants must have identical signature
                     """Set list of OpenGL uniform data."""
-                    c_array[:] = values
+                    # Support buffer protocol
+                    try:
+                        # FIXME: Configure the struct format on the uniform to support
+                        #        other types than float
+                        c_array[:] = struct.unpack(f"{length}f", values)
+                    except Exception:
+                        c_array[:] = values
+
                     gl_program_setter(program_id, location, array_length, ptr)
 
             else:

tests/unit/gl/test_gl_program.py

@@ -2,7 +2,7 @@
 import pytest
 import arcade
 from pyglet import gl
-from pyglet.math import Mat4
+from pyglet.math import Mat4, Mat3
 from arcade.gl import ShaderException
 from arcade.gl.uniform import UniformBlock
 from arcade.gl.glsl import ShaderSource
@@ -130,14 +130,15 @@ def test_program_basic(ctx):
         vertex_shader="""
         #version 330
 
+        uniform mat4 matrix;
         uniform vec2 pos_offset;
 
         in vec2 in_vert;
         in vec2 in_uv;
         out vec2 v_uv;
 
         void main() {
-            gl_Position = vec4(in_vert + pos_offset, 0.0, 1.0);
+            gl_Position = matrix * vec4(in_vert + pos_offset, 0.0, 1.0);
             v_uv = in_uv;
         }
         """,
@@ -166,6 +167,16 @@ def test_program_basic(ctx):
     with pytest.raises(KeyError):
         program['this_uniform_do_not_exist']
 
+    # uniform values using byte data. struct.unpack in uniform setters will read from
+    # objects supporting buffer protocol like glm and numpy types
+    mat44_bytes = b'\x00\x00\x80?\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80?\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80?\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80?'
+    program['matrix'] = mat44_bytes
+    assert program['matrix'] == Mat4()
+
+    # vectors
+    program['pos_offset'] = b'\x00\x00\x80?\x00\x00\x00@'
+    assert program['pos_offset'] == (1.0, 2.0)
+
 
 def test_vertex_shader(ctx):
     # Program with only vertex shader