glCompressedTexImage2D error

[konstantinegorov]

Hi!
I got the error "Uncaught TypeError TypeError: Failed to execute 'compressedTexImage2D' on 'WebGLRenderingContext': parameter 7 is not of type 'ArrayBufferView'", when I called glCompressedTexImage2D and passed null to the "data" parameter. How to avoid it? Is there any workaround?

[konstantinegorov]

Is there any update?

[sbc100]

Its hard to say what this might be without more details. Can you share a full backtrace? And the line of code at the call site? If possible a complete program would be even better.

There are several tests in the test directory can use glCompressedTexImage2D. It might be useful to take a look at test/browser/test_anisotropic.c, for example, to see if there is anything that you are doing differently.

[matusfedorko]

We started experiencing this problem too after upgrading from emscripten version 3.1.39 to version 3.1.64. Here is a minimal repro based on the anisotropic test:

#include "SDL/SDL.h"
#include "SDL/SDL_image.h"
#include "SDL/SDL_opengl.h"

#include <stdio.h>

int main(int argc, char *argv[])
{
    // Slightly different SDL initialization
    if ( SDL_Init(SDL_INIT_VIDEO) != 0 ) {
        printf("Unable to initialize SDL: %s\n", SDL_GetError());
        return 1;
    }

    SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 );

    SDL_Surface *screen = SDL_SetVideoMode( 600, 600, 16, SDL_OPENGL );
    if ( !screen ) {
        printf("Unable to set video mode: %s\n", SDL_GetError());
        return 1;
    }

    // Clear the screen before drawing
    glClear( GL_COLOR_BUFFER_BIT );

    glViewport( 0, 0, 600, 600 );

    GLuint texture;
    glGenTextures( 1, &texture );
    glBindTexture( GL_TEXTURE_2D, texture );
    glCompressedTexImage2D(GL_TEXTURE_2D, 0, GL_COMPRESSED_RGB_S3TC_DXT1_EXT, 4, 4, 0, 8, NULL);

    SDL_GL_SwapBuffers();

#ifndef __EMSCRIPTEN__
    // Wait for 3 seconds to give us a chance to see the image
    SDL_Delay(2000);
#endif

    // Now we can delete the OpenGL texture and close down SDL
    glDeleteTextures( 1, &texture );

    SDL_Quit();

    return 0;
}

Compile like this:

emcc test_anisotropic.c -g -s ALLOW_MEMORY_GROWTH=1 -s INITIAL_MEMORY=2000MB -s MAXIMUM_MEMORY=4000MB -s USE_WEBGL2=1 -s MIN_WEBGL_VERSION=1 -s MAX_WEBGL_VERSION=2 -o main.html

The output is:

main.js:3810 Uncaught TypeError: Failed to execute 'compressedTexImage2D' on 'WebGL2RenderingContext': parameter 7 is not of type 'ArrayBufferView'.
    at _glCompressedTexImage2D (main.js:3810:9)
    at __main_argc_argv (test_anisotropic.c:31)
    at main.js:634:12
    at callMain (main.js:3973:15)
    at doRun (main.js:4011:23)
    at main.js:4020:7

The two necessary conditions to reproduce the issue are to use glCompressedTexImage2D with NULL pointer for the last argument and to compile with memory limit greater than 2GB.

This is how glCompressedTexImage2D implementation looks in 3.1.39:

  glCompressedTexImage2D: function(target, level, internalFormat, width, height, border, imageSize, data) {
#if MAX_WEBGL_VERSION >= 2
    if ({{{ isCurrentContextWebGL2() }}}) { // WebGL 2 provides new garbage-free entry points to call to WebGL. Use those always when possible.
      if (GLctx.currentPixelUnpackBufferBinding || !imageSize) {
        GLctx.compressedTexImage2D(target, level, internalFormat, width, height, border, imageSize, data);
      } else {
        GLctx.compressedTexImage2D(target, level, internalFormat, width, height, border, HEAPU8, data, imageSize);
      }
      return;
    }
#endif
    GLctx.compressedTexImage2D(target, level, internalFormat, width, height, border, data ? {{{ makeHEAPView('U8', 'data', 'data+imageSize') }}} : null);
  },

And this is how it looks in 3.1.64:

  glCompressedTexImage2D: (target, level, internalFormat, width, height, border, imageSize, data) => {
#if MAX_WEBGL_VERSION >= 2
    if ({{{ isCurrentContextWebGL2() }}}) {
      if (GLctx.currentPixelUnpackBufferBinding || !imageSize) {
        GLctx.compressedTexImage2D(target, level, internalFormat, width, height, border, imageSize, data);
        return;
      }
#if WEBGL_USE_GARBAGE_FREE_APIS
      GLctx.compressedTexImage2D(target, level, internalFormat, width, height, border, HEAPU8, data, imageSize);
      return;
#endif
    }
#endif
    GLctx.compressedTexImage2D(target, level, internalFormat, width, height, border, data ? {{{ makeHEAPView('U8', 'data', 'data+imageSize') }}} : null);
  },

The different part is WEBGL_USE_GARBAGE_FREE_APIS which is false with higher memory limit. I don't know enough about emscripten to fix this properly, but hopefully now the issue will get addressed.

[kripken]

Thanks for the testcase @matusfedorko , I bisected this to "Avoid garbage-free WebGL APIs when memory size is over 2gb." (#21445)

@sbc100 PTAL

[sbc100]

What is the glCompressedTexImage2D supposed to be doing here: glCompressedTexImage2D(GL_TEXTURE_2D, 0, GL_COMPRESSED_RGB_S3TC_DXT1_EXT, 4, 4, 0, 8, NULL);?

i.e. what does it mean to set the pixels argument to NULL?

It seems like before #21445 we would end up calling GLctx.compressedTexImage2D(target, level, internalFormat, width, height, border, HEAPU8, data, imageSize); which I think would read imageSize bytes from address zero (data is zero/null) of the main memoy.. which seem wrong.

I'm not sure how this is supposed to work I guess. @juj might know? Also @kainino0x ?

[sbc100]

According the MDN docs it should be possible to call compressedTexImage2D with only 6 arguments. But according the errors I'm seeing in chrome it is requiring the a 7th argument.

[sbc100]

Actually the 6 argument version fails here with webgl1 too: TypeError: Failed to execute 'compressedTexImage2D' on 'WebGLRenderingContext': 7 arguments required, but only 6 present.

[sbc100]

So this code also fails without memory growth on WebGL1: TypeError: Failed to execute 'compressedTexImage2D' on 'WebGLRenderingContext': parameter 7 is not of type 'ArrayBufferView'.

[sbc100]

Doing a little research it sounds like passing null for pixels is generally don't to reserve space for following calls to glCompressedTexSubImage2D? Is that why you are passing null in this case?

From the docs it looks like maybe glTexImage2D supports this null but glCompressedTexSubImage2D does not?

See: https://community.khronos.org/t/glcompressedteximage2d-and-null-data/41505
And: https://registry.khronos.org/OpenGL-Refpages/gl4/html/glTexImage2D.xhtml
And: https://registry.khronos.org/OpenGL-Refpages/gl4/html/glCompressedTexImage2D.xhtml

Node that glTexImage2D mentions "data may be a null pointer. In this case, texture memory is allocated to accommodate a texture of width width and height height." but glCompressedTexImage2D docs do no say this.

ping @kainino0x @juj

[matusfedorko]

Yes, we pass NULL to allocate space for the texture. I tried that suggestion with glTexImage2D, but it does not work. In desktop GL (NVidia) the output is all black and in Chrome I get some error (I don't remember what it was exactly, but if you want you can try to modify the repro sample). I also noticed that reference docs do not explicitly mention NULL, but docs are not specification and it seems only logical to me that glCompressedTexImage2D/glCompressedTexSubImage2D would behave analogously to glTexImage2D/glTexSubImage2D.

[matusfedorko]

Actually. in the OpenGL 4.6 specification (https://registry.khronos.org/OpenGL/specs/gl/glspec46.core.pdf) on page 230 I found this:

If the data argument of CompressedTexImage1D, CompressedTexImage2D, or CompressedTexImage3D is NULL, and the pixel unpack buffer object is zero, a texture image with unspecified image contents is created, just as when a NULL pointer is passed to TexImage1D, TexImage2D, or TexImage3D.

[sbc100]

Sadly i looks like I can't omit the last argument or set it to null using WebGL2's compressedTexImage2D. See #19300 (comment).

I wonder if this is bug since https://developer.mozilla.org/en-US/docs/Web/API/WebGLRenderingContext/compressedTexImage2D mentions a six argument version in WebGL1 and says that that WebGL API adds overloads.

[sbc100]

Perhaps we can map compressedTexImage2D to texImage2D internally in the case the pixels is NULL. According the webgl spec pixels cannot be null for compressedTexImage2D, only for texImage2D, although that might be an oversight in the spec?

https://registry.khronos.org/webgl/specs/latest/1.0/#COMPRESSEDTEXIMAGE2D

texImage2D in the same doc says "If pixels is null, a buffer of sufficient size initialized to 0 is passed." and indeed has a signature where the final argument is optional unlike compressedTexImage2D.

@kenrussell maybe you can help here?

[matusfedorko]

And how about the first overload compressedTexImage2D(target, level, internalformat, width, height, border) ? I don't see any way to pass a pointer to data to it, so I assume it must be intended for the texture allocation use case. Otherwise it would be useless. Alternatively the GLctx.compressedTexImage2D(target, level, internalFormat, width, height, border, HEAPU8, data, imageSize); version seems to work well as a workaround.

[matusfedorko]

Well, so I did some tests. That overload did not work (maybe because I have WebGL 2 context and not 1), but GLctx.compressedTexImage2D(target, level, internalFormat, width, height, border, HEAPU8, data, imageSize); works fine. glTexImage2D generates WebGL: INVALID_OPERATION: texImage2D: compressed texture formats are not accepted