iOS app crashes on creating Texture

[Raki]

I'm trying to render a texture quad by following the "hello-triangle" example on iOS. My new material to render the quad is proper as it is drawing a black quad if I didn't bind any texture to material instance. But when I call this function to create texture, it is crashing at generateMipmaps(*engine)

void loadTexture(Engine* engine, const std::string& filePath, Texture** map, bool sRGB)
{
int w, h, n;
unsigned char* data = stbi_load(path.c_str(), &w, &h, &n, 3);
if (data != nullptr) {
*map = Texture::Builder()
.width(uint32_t(w))
.height(uint32_t(h))
.levels(0xff)
.format(sRGB?driver::TextureFormat::SRGB8:driver::TextureFormat::RGB8)
.build(*engine);
Texture::PixelBufferDescriptor buffer(data, size_t(w * h * 3),
Texture::Format::RGB, Texture::Type::UBYTE,
(driver::BufferDescriptor::Callback) &stbi_image_free);
(*map)->setImage(*engine, 0, std::move(buffer));
(*map)->generateMipmaps(*engine);
}

I pulled this function from Desktop samples of filament.
I tried tweaking png compression options on xCode but no luck.

• Device: iPhone 7
• OS: iOS 11.4.1

[bejado]

Which backend are you using, OpenGL? I think there were some changes recently to mipmap generation, but it's possible this is specific to iOS. Is there any particular message logged before crashing?

[Raki]

if format is RGB8 then log is

019-02-14 10:35:51.922809+0530 FilamentDemo[291:12092] [DYMTLInitPlatform] platform initialization successful
FEngine (64 bits) created at 0x104800000 (threading is enabled)
FEngine resolved backend: OpenGL
2019-02-14 10:35:52.216054+0530 FilamentDemo[291:12101] Metal GPU Frame Capture Enabled
2019-02-14 10:35:52.217089+0530 FilamentDemo[291:12101] Metal API Validation Enabled
N5utils18PostconditionPanicE
in virtual void filament::PlatformCocoaTouchGL::makeCurrent(filament::driver::Platform::SwapChain *, filament::driver::Platform::SwapChain *):129
reason: Incomplete framebuffer.
#0 0 libsystem_pthread.dylib 0x0000000184cd1110 + 0
libc++abi.dylib: terminating with uncaught exception of type utils::PostconditionPanic

if format is SRGB8 then log is

2019-02-14 10:38:53.261018+0530 FilamentDemo[297:13117] [DYMTLInitPlatform] platform initialization successful
FEngine (64 bits) created at 0x109800000 (threading is enabled)
FEngine resolved backend: OpenGL
2019-02-14 10:38:53.542747+0530 FilamentDemo[297:13125] Metal GPU Frame Capture Enabled
2019-02-14 10:38:53.543834+0530 FilamentDemo[297:13125] Metal API Validation Enabled
N5utils18PostconditionPanicE
in void filament::details::FTexture::generateMipmaps(filament::details::FEngine &) const:199
reason: Texture format must be color renderable
0 FilamentDemo 0x0000000104e8b08c -[FilamentView initializeFilamentQuad] + 1388
1 0 FilamentDemo 0x0000000104e8a5f8 -[FilamentView initWithCoder:] + 180
2 0 UIKit 0x000000018f32cfec + 248
3 0 UIKit 0x000000018f48e738 + 688
4 0 UIKit 0x000000018f48e470 + 312
5 0 UIKit 0x000000018f32cc94 + 188
6 0 UIKit 0x000000018f48e738 + 688
7 0 UIKit 0x000000018f48e8b0 + 1064
8 0 UIKit 0x000000018f48e470 + 312
9 0 UIKit 0x000000018f32bfe4 + 1164
10 0 UIKit 0x000000018f15daa8 + 372
11 0 UIKit 0x000000018eda1074 + 176
12 0 UIKit 0x000000018ecc5b14 + 172
13 0 UIKit 0x000000018ecc5a50 + 28
14 0 UIKit 0x000000018ecb6ce4 + 136
15 0 UIKit 0x000000018ecb5b18 + 272
16 0 UIKit 0x000000018ed4362c + 48
17 0 UIKit 0x000000018ecb9274 + 3660
libc++abi.dylib: terminating with uncaught exception of type utils::PostconditionPanic

[bejado]

I don't think iOS supports RGB colorbuffers, hence the "Texture format must be color renderable." assertion. Can you try with a RGBA texture and see if that succeeds?

[Raki]

tried with format driver::TextureFormat::RGBA8 got the following error

2019-02-14 10:47:16.609869+0530 FilamentDemo[302:15292] [DYMTLInitPlatform] platform initialization successful
FEngine (64 bits) created at 0x107800000 (threading is enabled)
FEngine resolved backend: OpenGL
2019-02-14 10:47:16.876139+0530 FilamentDemo[302:15301] Metal GPU Frame Capture Enabled
2019-02-14 10:47:16.877123+0530 FilamentDemo[302:15301] Metal API Validation Enabled
N5utils18PostconditionPanicE
in virtual void filament::PlatformCocoaTouchGL::makeCurrent(filament::driver::Platform::SwapChain *, filament::driver::Platform::SwapChain *):129
reason: Incomplete framebuffer.
#0 0 libsystem_pthread.dylib 0x0000000184cd1110 + 0
libc++abi.dylib: terminating with uncaught exception of type utils::PostconditionPanic

with format driver::TextureFormat::SRGBA8 got the following error

2019-02-14 10:49:25.732349+0530 FilamentDemo[308:16078] [DYMTLInitPlatform] platform initialization successful
FEngine (64 bits) created at 0x1037d8000 (threading is enabled)
FEngine resolved backend: OpenGL
2019-02-14 10:49:26.002348+0530 FilamentDemo[308:16086] Metal GPU Frame Capture Enabled
2019-02-14 10:49:26.003308+0530 FilamentDemo[308:16086] Metal API Validation Enabled
N5utils18PostconditionPanicE
in void filament::details::FTexture::generateMipmaps(filament::details::FEngine &) const:199
reason: Texture format must be color renderable

[bejado]

Okay, potentially something else going on- will take a closer look.

[romainguy]

This error triggers when isRenderTargetFormatSupported() returns false in the driver. Maybe it's just that it wasn't implemented properly for iOS?

[bejado]

@Raki just merged a fix- can pull and try again? Note that sRGB textures (correctly) do not support mipmap generation on iOS.

[Raki]

Hi @bejado , I tried with latest code, no crashes so far.
But the texture quad I am drawing with unlit material is coming like this.

While debugging i can see like, the texture is being updated with current frame.
I'm using format as driver::TextureFormat::RGBA8

[bejado]

Does that only happen when you generate mipmaps? Can you show your material file?

[Raki]

@bejado , I tried disabling mipmaps but no change in output.
I'm using the following material .

material
{
name : simple_tex,
shadingModel : unlit,
parameters : [
// Base color sRGB texture
{
type : sampler2d,
name : albedo
}
],
// To sample textures our material must declare that it requires
// a set of UV coordinates from the rendered mesh
requires: [
uv0
]
}

fragment {
void material(inout MaterialInputs material) {
prepareMaterial(material);
material.baseColor = texture(materialParams_albedo, getUV0());
}
}

[bejado]

I don't see anything wrong with the material. Are you creating a sampler and setting it as a parameter on your material instance?

TextureSampler sampler(TextureSampler::MinFilter::LINEAR, TextureSampler::MagFilter::LINEAR);
materialInstance = material->createInstance();
materialInstance->setParameter("albedo", texture, sampler);

It would help if you could post all the changes you've made to HelloTriangle.

[Raki]

@bejado The following are the changes I made to HelloTriangle Demo.

struct Vertex3
{
    math::float2 pos;
    math::float2 uv;
};

static const Vertex3 QUAD_VERTICES[4] = {
    {{-0.5,-0.5}, {0,0}},
    {{0.5,-0.5}, {1,0}},
{{0.5,0.5}, {1,1}},
{{-0.5,0.5}, {0,1}}
};

static constexpr uint16_t QUAD_INDICES[6] = {0,1,2,0,2,3};

-(void) initializeFilamentQuad
{
    engine = Engine::create(filament::Engine::Backend::OPENGL);
    swapChain = engine->createSwapChain((__bridge void*) self.layer);
    renderer = engine->createRenderer();
    scene = engine->createScene();
    camera = engine->createCamera();
    
    filaView = engine->createView();
    filaView->setClearColor({0.1, 0.125, 0.25, 1.0});
    filaView->setPostProcessingEnabled(false);
    filaView->setDepthPrepass(filament::View::DepthPrepass::DISABLED);
    
    int stride = sizeof(float)*4;
    
    app.vb = VertexBuffer::Builder()
    .vertexCount(4)
    .bufferCount(1)
    .attribute(VertexAttribute::POSITION, 0, VertexBuffer::AttributeType::FLOAT2, 0, stride)
    .attribute(VertexAttribute::UV0, 0, VertexBuffer::AttributeType::FLOAT2, 8, stride)
    .build(*engine);
    app.vb->setBufferAt(*engine, 0,
                        VertexBuffer::BufferDescriptor(QUAD_VERTICES, stride*4, nullptr));
    
    app.ib = IndexBuffer::Builder()
    .indexCount(6)
    .bufferType(IndexBuffer::IndexType::USHORT)
    .build(*engine);
    app.ib->setBuffer(*engine,
                      IndexBuffer::BufferDescriptor(QUAD_INDICES, sizeof(uint16_t)*6, nullptr));
    
    app.mat = Material::Builder()
    .package((void*) SIMPLE_TEXR_PACKAGE, sizeof(SIMPLE_TEXR_PACKAGE))
    .build(*engine);
    
    materialInstance = app.mat->getDefaultInstance();
    
    NSString *bcPath = [[NSBundle mainBundle] pathForResource:@"Model_1_txt" ofType:@"png"];
    const char *bcPath_cstr = [bcPath fileSystemRepresentation];

    TextureLoader::loadTexture(engine,string(bcPath_cstr),&albedo);
    TextureSampler *sampler = new TextureSampler(TextureSampler::MinFilter::LINEAR,TextureSampler::MagFilter::LINEAR);
    materialInstance->setParameter("albedo", albedo, *sampler);
    
    
    
    app.renderable = EntityManager::get().create();
    RenderableManager::Builder(1)
    .boundingBox({{ -1, -1, -1 }, { 1, 1, 1 }})
    .material(0, materialInstance)
    .geometry(0, RenderableManager::PrimitiveType::TRIANGLES, app.vb, app.ib, 0, 6)
    .culling(false)
    .receiveShadows(false)
    .castShadows(false)
    .build(*engine, app.renderable);
    scene->addEntity(app.renderable);
    
     
    filaView->setScene(scene);
    filaView->setCamera(camera);
    CGRect nativeBounds = [UIScreen mainScreen].nativeBounds;
    filaView->setViewport(Viewport(0, 0, nativeBounds.size.width, nativeBounds.size.height));
    
    
    constexpr float ZOOM = 1.5f;
    const uint32_t w = filaView->getViewport().width;
    const uint32_t h = filaView->getViewport().height;
    const float aspect = (float) w / h;
    camera->setProjection(Camera::Projection::ORTHO,
                          -aspect * ZOOM, aspect * ZOOM,
                          -ZOOM, ZOOM, 0, 1);
}

//loadTexture code 
        int w, h, n;
        unsigned char* data = stbi_load(path.c_str(), &w, &h, &n, 4);
        if (data != nullptr) {
            *map = Texture::Builder()
            .width(uint32_t(w))
            .height(uint32_t(h))
            .levels(0xff)
            .format(driver::TextureFormat::RGBA8)
            .build(*engine);
            Texture::PixelBufferDescriptor buffer(data, size_t(w * h * 4),
                                                  Texture::Format::RGBA, Texture::Type::UBYTE,
                                                  (driver::BufferDescriptor::Callback) &stbi_image_free);
            (*map)->setImage(*engine, 0, std::move(buffer));
            (*map)->generateMipmaps(*engine);

[bejado]

Can you try replacing

    materialInstance = app.mat->getDefaultInstance();

with

    materialInstance = app.mat->createInstance();

This might be a bug on our side.

[Raki]

@bejado Yes, it worked with app.mat->createInstance(); . Thank you very much.

[bejado]

Sure thing! Note that you should be able to use getDefaultInstance so that is in fact a bug on our part which will be fixed in #854.