export btHeightfieldTerrainShape to PyBullet. Note that tinyrenderer doesn't support rendering it (it would be too slow on CPU)

fix rare getKeyboardEvents threading issue
change texture color to default plane.urdf blue

examples/Heightfield/HeightfieldExample.cpp

@@ -491,8 +491,22 @@ getRawHeightfieldData
                     for (int j = 0; j < width; ++j)
                     {
                         float y = j * s_gridSpacing;
-                        float z = double(image[i*3+width*j*3])*(40./256.);
+                        float z = double(image[i*3+width*j*3])*(14./256.);
                         convertFromFloat(p, z, type);
+						// update min/max
+						if (!i && !j) {
+							minHeight = z;
+							maxHeight = z;
+						}
+						else {
+							if (z < minHeight) {
+								minHeight = z;
+							}
+							if (z > maxHeight) {
+								maxHeight = z;
+							}
+						}
+
                         p += bytesPerElement;
                     }
                 }
@@ -574,6 +588,19 @@ getRawHeightfieldData
                         float y = j * s_gridSpacing;
                         float z = allValues[i+width*j];
                         convertFromFloat(p, z, type);
+						// update min/max
+						if (!i && !j) {
+							minHeight = z;
+							maxHeight = z;
+						}
+						else {
+							if (z < minHeight) {
+								minHeight = z;
+							}
+							if (z > maxHeight) {
+								maxHeight = z;
+							}
+						}
                         p += bytesPerElement;
                     }
                 }
@@ -1159,11 +1186,11 @@ void HeightfieldExample::resetPhysics(void)
 	// set origin to middle of heightfield
 	btTransform tr;
 	tr.setIdentity();
-	tr.setOrigin(btVector3(0, 0, 0));
+	tr.setOrigin(btVector3(0, 0, -4));
 
 	if (m_model== eImageFile)
 	{
-		tr.setOrigin(btVector3(0, 0, -24));
+		
 		b3BulletDefaultFileIO fileIO;
 		char relativeFileName[1024];
 		int found = fileIO.findFile("heightmaps/gimp_overlay_out.png", relativeFileName, 1024);