Offscreen Rendering in float32 precision

pyrender/constants.py

@@ -54,6 +54,8 @@ class RenderFlags(object):
     FLAT = 4096
     """Render the color buffer flat, with no lighting computations."""
     SEG = 8192
+    """Return a float32 color buffer instead of default uint8."""
+    COLOR_FLOAT32 = 16384
 
 
 class TextAlign:

pyrender/offscreen.py

@@ -106,7 +106,7 @@ def render(self, scene, flags=RenderFlags.NONE, seg_node_map=None):
             if flags & RenderFlags.DEPTH_ONLY:
                 retval = depth
             else:
-                color = self._renderer.read_color_buf()
+                color = self._renderer.read_color_buf(flags)
                 retval = color, depth
 
         # Make the platform not current

pyrender/renderer.py

@@ -218,25 +218,37 @@ def render_text(self, text, x, y, font_name='OpenSans-Regular',
         # Draw text
         font.render_string(text, x, y, scale, align)
 
-    def read_color_buf(self):
+    def read_color_buf(self, flags=RenderFlags.NONE):
         """Read and return the current viewport's color buffer.
 
         Alpha cannot be computed for an on-screen buffer.
 
         Returns
         -------
-        color_im : (h, w, 3) uint8
+        color_im : (h, w, 3) uint8 COLOR_FLOAT32 flag is not set in flags, otherwise float32
             The color buffer in RGB byte format.
         """
         # Extract color image from frame buffer
         width, height = self.viewport_width, self.viewport_height
         glBindFramebuffer(GL_READ_FRAMEBUFFER, 0)
         glReadBuffer(GL_FRONT)
-        color_buf = glReadPixels(0, 0, width, height, GL_RGB, GL_UNSIGNED_BYTE)
-
-        # Re-format them into numpy arrays
-        color_im = np.frombuffer(color_buf, dtype=np.uint8)
-        color_im = color_im.reshape((height, width, 3))
+        if flags & RenderFlags.RGBA:
+            glformat = GL_RGBA
+            npshape = (height, width, 4)
+        else:
+            glformat = GL_RGB
+            npshape = (height, width, 3)
+        if flags & RenderFlags.COLOR_FLOAT32:
+            gltype = GL_FLOAT
+            npdtype = np.float32
+        else:
+            gltype = GL_UNSIGNED_BYTE
+            npdtype = np.uint8
+        color_buf = glReadPixels(
+            0, 0, width, height, glformat, gltype,
+        )
+        color_im = np.frombuffer(color_buf, dtype=npdtype)
+        color_im = color_im.reshape(npshape)
         color_im = np.flip(color_im, axis=0)
 
         # Resize for macos if needed
@@ -1009,7 +1021,7 @@ def _configure_forward_pass_viewport(self, flags):
 
         # If using offscreen render, bind main framebuffer
         if flags & RenderFlags.OFFSCREEN:
-            self._configure_main_framebuffer()
+            self._configure_main_framebuffer(flags)
             glBindFramebuffer(GL_DRAW_FRAMEBUFFER, self._main_fb_ms)
         else:
             glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0)
@@ -1051,7 +1063,7 @@ def _delete_shadow_framebuffer(self):
         if self._shadow_fb is not None:
             glDeleteFramebuffers(1, [self._shadow_fb])
 
-    def _configure_main_framebuffer(self):
+    def _configure_main_framebuffer(self, flags):
         # If mismatch with prior framebuffer, delete it
         if (self._main_fb is not None and
                 self.viewport_width != self._main_fb_dims[0] or
@@ -1065,7 +1077,7 @@ def _configure_main_framebuffer(self):
 
             glBindRenderbuffer(GL_RENDERBUFFER, self._main_cb)
             glRenderbufferStorage(
-                GL_RENDERBUFFER, GL_RGBA,
+                GL_RENDERBUFFER, GL_RGBA32F if flags & RenderFlags.COLOR_FLOAT32 else GL_RGBA,
                 self.viewport_width, self.viewport_height
             )
 
@@ -1090,7 +1102,7 @@ def _configure_main_framebuffer(self):
             self._main_cb_ms, self._main_db_ms = glGenRenderbuffers(2)
             glBindRenderbuffer(GL_RENDERBUFFER, self._main_cb_ms)
             glRenderbufferStorageMultisample(
-                GL_RENDERBUFFER, 4, GL_RGBA,
+                GL_RENDERBUFFER, 4, GL_RGBA32F if flags & RenderFlags.COLOR_FLOAT32 else GL_RGBA,
                 self.viewport_width, self.viewport_height
             )
             glBindRenderbuffer(GL_RENDERBUFFER, self._main_db_ms)
@@ -1172,17 +1184,22 @@ def _read_main_framebuffer(self, scene, flags):
 
         # Read color
         if flags & RenderFlags.RGBA:
-            color_buf = glReadPixels(
-                0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE
-            )
-            color_im = np.frombuffer(color_buf, dtype=np.uint8)
-            color_im = color_im.reshape((height, width, 4))
+            glformat = GL_RGBA
+            npshape = (height, width, 4)
         else:
-            color_buf = glReadPixels(
-                0, 0, width, height, GL_RGB, GL_UNSIGNED_BYTE
-            )
-            color_im = np.frombuffer(color_buf, dtype=np.uint8)
-            color_im = color_im.reshape((height, width, 3))
+            glformat = GL_RGB
+            npshape = (height, width, 3)
+        if flags & RenderFlags.COLOR_FLOAT32:
+            gltype = GL_FLOAT
+            npdtype = np.float32
+        else:
+            gltype = GL_UNSIGNED_BYTE
+            npdtype = np.uint8
+        color_buf = glReadPixels(
+            0, 0, width, height, glformat, gltype,
+        )
+        color_im = np.frombuffer(color_buf, dtype=npdtype)
+        color_im = color_im.reshape(npshape)
         color_im = np.flip(color_im, axis=0)
 
         # Resize for macos if needed

tests/unit/test_offscreen.py

@@ -1,8 +1,9 @@
 import numpy as np
 import trimesh
+import pytest
 
 from pyrender import (OffscreenRenderer, PerspectiveCamera, DirectionalLight,
-                      SpotLight, Mesh, Node, Scene)
+                      SpotLight, Mesh, Node, Scene, RenderFlags)
 
 
 def test_offscreen_renderer(tmpdir):
@@ -83,10 +84,22 @@ def test_offscreen_renderer(tmpdir):
     _ = scene.add(cam, pose=cam_pose)
 
     r = OffscreenRenderer(viewport_width=640, viewport_height=480)
-    color, depth = r.render(scene)
+    color_u8, depth = r.render(scene)
+    r.delete()
 
-    assert color.shape == (480, 640, 3)
+    assert color_u8.shape == (480, 640, 3)
+    assert color_u8.dtype == np.uint8
     assert depth.shape == (480, 640)
     assert np.max(depth.data) > 0.05
     assert np.count_nonzero(depth.data) > (0.2 * depth.size)
+
+    # render in floating point
+    r = OffscreenRenderer(viewport_width=640, viewport_height=480)
+    color_f32, depth = r.render(scene, RenderFlags.COLOR_FLOAT32)
     r.delete()
+    assert color_f32.shape == (480, 640, 3)
+    assert color_f32.dtype == np.float32
+
+    delta = np.abs(color_f32*255 - color_u8.astype(np.float32))
+    assert np.percentile(delta, 99.9) <= 1
+    assert np.max(delta) < 3