2
$\begingroup$

With WebGL 1 we can use WEBGL_draw_buffers extension which lets us use a texture as the depth attachment on the frame buffer.

And we can chose to use LINEAR or NEAREST as the filtering method.

gl.getExtension('WEBGL_draw_buffers');
gl.texImage2D(gl.TEXTURE_2D, 0, gl.DEPTH_COMPONENT, width, height, 0, gl.DEPTH_COMPONENT, gl.UNSIGNED_SHORT, null);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);

WebGL 2 doesn't require an extension for this, but as soon as I switched to WebGL 2 I noticed that nothing happens unless I use NEAREST as the filtering method.

gl.texImage2D(gl.TEXTURE_2D, 0, gl.DEPTH_COMPONENT24, width, height, 0, gl.DEPTH_COMPONENT, gl.UNSIGNED_INT, null);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR); // wont work
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR); // has to be NEAREST

Is there something I have to do to make this possible?

The only workaround for this that I know of would be to draw this depth texture onto another texture, but that seems like a waste of time.

Improve this question
$\endgroup$
5
  • $\begingroup$ If linear is not supported then you could read 4 texels and then do bilinear interpolation of the values yourself in the shader ? $\endgroup$
    – PaulHK
    Apr 14 '20 at 6:23
  • $\begingroup$ have you tried enabling the extensions OES_texture_half_float_linear and OES_texture_float_linear? $\endgroup$
    – user13167
    Apr 14 '20 at 14:18
  • $\begingroup$ @Marvin I have, nothing changed, even after I switched to DEPTH_COMPONENT32F it still only works with NEAREST. But from your tone it sounds like it should have worked. All examples I managed to find used NEAREST, but maybe you know some examples that don't? $\endgroup$
    – zoran404
    Apr 14 '20 at 17:33
  • $\begingroup$ @PaulHK Are you suggesting that 4 reads per fragment would be faster than drawing the depth texture onto another l texture that has a linear filter? $\endgroup$
    – zoran404
    Apr 14 '20 at 17:36
  • $\begingroup$ @zoran404 not really, I just came across this question and thought it was worth a quick check before I looked any further (I've not really worked with textures yet, so this is a learning exercise for me too). $\endgroup$
    – user13167
    Apr 14 '20 at 18:29
3
$\begingroup$

The spec says depth textures are not filterable.

3.8.13

...

Using the preceding definitions, a texture is complete unless any of the following conditions hold true:

  • The effective internal format specified for the texture arrays is a sized internal depth or depth and stencil format (see table 3.14), the value of TEXTURE_COMPARE_MODE is NONE, and either the magnification filter is not NEAREST or the minification filter is neither NEAREST nor NEAREST_- MIPMAP_NEAREST
Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.