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OpenGL Mip mapping issue

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I am busy writing a directx renderer for my engine that up until now was opengl only. Here is a screenshot rendered in opengl that demonstrates what Im trying to achieve.




Here is the same scene rendered in directx




Looking at the far away terrain the mipmapping in the directx version seems a bit of (well I think its the mipmapping). You can clearly see some ugly patterns forming the further you go.


The only only difference between the 2 (that i can think of) is the way the mip maps are generated. In the opengl one the mipmaps are created using gluBuild2DMipmaps. In the direcx one I generate the mipmaps myself and i  simply average the nearest 4 pixels together when downscaling. So my first thought was that gluBuild2DMipmaps uses a different algorithm to downscale the image but I cant seem to find more information on it. Maybe the problem is something else entirely? Either way any help will appreciated.


Thnx in Advance!





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Since gluBuild2DMipmaps is more of a utility function to get things running than a final solution, I would be surprised if it was doing anything more complicated than a simple box filter (like what you're doing in your DirectX version right now). 


However, you can rule out gluBuild2DMipmaps as the source of your problem by simply doing the same thing you do in DirectX in OpenGL. Have you tried generating mips yourself in OpenGL, the same way you do in DirectX, and seeing if that produces results that look the same?


Also, are you sure your DirectX mip map generation is correct? Have you looked at the generated mips directly and verified that they're correct? It can be kind of hard to tell just from an in-game screenshot whether the mips are exactly right (or exactly what you're expecting, since "right" is kind of subjective).

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Which texture filter mode are you using when rendering?



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Can you provide the code that shows how you generate and use the texture?


Why aren't you using DirectX functions (When creating the resource or with GenerateMipMaps)?


Also, make sure you're rendering state is correct - you didn't specify which DX version you are using, but it can be due to incorrect ShaderResourceView::MipLevels and SamplerState::MaxLod fields.

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GenerateMips is only valid if the base resource is created with D3D11_BIND_RENDER_TARGET (you don't say which D3D version you're using here so I'm assuming 11).


Per-spec, gluBuild2DMipmaps uses a box filter, which is exactly what you say you're using for your D3D code, so the error may be in your box filter code.


What I'd advise you check first, however, is your D3D sampler states.  The min/mag/mip filtering modes work quite differently in D3D than they do in GL, with sampler states being decoupled from the textures rather than being part of a texture object, so this is one likely source of error: I consider it at least possible that this is wrong and you've ended up with a nearest filter where you probably want min/map/mip linear.


(Yes, later versions of GL have sampler objects too, but I'm assuming - from mention of gluBuild2DMapmaps - that the OP is using an earlier version.)

Edited by mhagain

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I use directX 11. And yes the opengl is quite a bit older. 


filter options in opengl:


filter options in directx
D3D11_SAMPLER_DESC sampDesc;
ZeroMemory(&sampDesc, sizeof(sampDesc));
sampDesc.Filter = D3D11_FILTER_MIN_MAG_MIP_LINEAR;
sampDesc.AddressU = D3D11_TEXTURE_ADDRESS_WRAP;
sampDesc.AddressV = D3D11_TEXTURE_ADDRESS_WRAP;
sampDesc.AddressW = D3D11_TEXTURE_ADDRESS_WRAP;
sampDesc.ComparisonFunc = D3D11_COMPARISON_NEVER;
sampDesc.MinLOD = 0;
sampDesc.MaxLOD = D3D11_FLOAT32_MAX;
Shaders. The first 4 textures contain height, normal and tile weight information. the next 8 textures are the actual colour textures for the terrain. all textures and samplers are bound to the vertex and pixel shader using the same slots (for compatibility with opengl). The pixel shader contains 1 sampler for each texture but theyre all the same. The vertex shader is probaly pretty irrelevent to the question.
vertex shader
Texture2D tex1  : register( t0 );
SamplerState samp1  : register( s0 );
Texture2D tex2  : register( t1 );
SamplerState samp2  : register( s1 );
Texture2D tex3  : register( t2 );
SamplerState samp3  : register( s2 );
Texture2D tex4  : register( t3 );
SamplerState samp4  : register( s3 );
  struct VSInput
float4 pos : a_position;
float2 textCoordA : v_textCoordA;
  struct PSInput
  float4 pos : SV_Position;
  float3 p : v_pos;
float2 textCoordA : v_textCoordA;
float3 normal : v_normal;
float2 gridPos : v_gridPos;
float w1 : v_w1;
float w2 : v_w2;
float w3 : v_w3;
float w4 : v_w4;
float w5 : v_w5;
float w6 : v_w6;
float w7 : v_w7;
float w8 : v_w8;
float2 c : v_c;
PSInput main(VSInput attrib)
        PSInput ps;
float4 vpos = attrib.pos;
ps.gridPos = float2(vpos.x*128,vpos.y*128);
float2 coord = float2(vpos.x/(8*lod)+tOffset.x,vpos.y/(8*lod)+tOffset.y);
ps.c = coord;
coord.x = clamp(coord.x,1.0/1024.0,1023.0/1024.0);
coord.y = clamp(coord.y,1.0/1024.0,1023.0/1024.0);
coord = float2(coord.x+1.0/2048, coord.y+1.0/2048);
float2 ic = float2(vpos.x/(8*lod)+tOffset.x,vpos.y/(8*lod)+tOffset.y);
ic = ic * 1024;
ic.x = clamp(ic.x,1.0,1023.0);
ic.y = clamp(ic.y,1.0,1023.0);
uint3 ici = uint3(ic.x,ic.y,0);
float4 t1 = tex1.Load(ici);
float4 t2 = tex2.Load(ici);
float4 t3 = tex3.Load(ici);
float4 t4 = tex4.Load(ici);
float h = (t1.r-(127.0/255.0)) * 65280.0 +
 t1.g * 255.0 +
                  t1.b * 1.0;
vpos.z = vpos.z + h;
ps.normal =  t2.rgb*2-1;
float4 vertPos = mul(vpos,modelMatrix);
    ps.pos = mul(vertPos,projectionAndViewMatrix);
    ps.p = vertPos.xyz;
    ps.w1 = t3.r;
    ps.w2 = t3.g;
    ps.w3 = t3.b;
    ps.w4 = t3.a;
    ps.w5 = t4.r;
    ps.w6 = t4.g;
    ps.w7 = t4.b;
    ps.w8 = t4.a;
    ps.textCoordA = attrib.textCoordA*(8.0/lod);
    return ps;
Pixel shader
Texture2D tex1  : register( t0 );
Texture2D tile1  : register( t4 );
Texture2D tile2  : register( t5 );
Texture2D tile3  : register( t6 );
Texture2D tile4  : register( t7 );
Texture2D tile5  : register( t8 );
Texture2D tile6  : register( t9 );
Texture2D tile7  : register( t10 );
Texture2D tile8  : register( t11 );
SamplerState samp1  : register( s4 );
SamplerState samp2  : register( s5 );
SamplerState samp3  : register( s6 );
SamplerState samp4  : register( s7 );
SamplerState samp5  : register( s8 );
SamplerState samp6  : register( s9 );
SamplerState samp7  : register( s10 );
SamplerState samp8  : register( s11 );
  struct PSInput
  float4 pos : SV_Position;
  float3 p : v_pos;
float2 textCoordA : v_textCoordA;
float3 normal : v_normal;
float2 gridPos : v_gridPos;
float w1 : v_w1;
float w2 : v_w2;
float w3 : v_w3;
float w4 : v_w4;
float w5 : v_w5;
float w6 : v_w6;
float w7 : v_w7;
float w8 : v_w8;
float2 c : v_c;
float4 main(PSInput ps) : SV_Target
uint x = int(floor(ps.p.x));
uint y = int(floor(ps.p.y));
x = x % 1024;
y = y % 1024;
float4 t1 = tex1.Load(uint3(ps.c.x*1024,ps.c.y*1024,0));
if (t1.a == 0.0) //indicates a hole in the terrain. Caves etc.
float3 n = normalize(ps.normal);
float4 c1 = tile1.Sample(samp1, ps.textCoordA);
float4 c2 = tile2.Sample(samp2, ps.textCoordA);
float4 c3 = tile3.Sample(samp3, ps.textCoordA);
float4 c4 = tile4.Sample(samp4, ps.textCoordA);
float4 c5 = tile5.Sample(samp5, ps.textCoordA);
float4 c6 = tile6.Sample(samp6, ps.textCoordA);
float4 c7 = tile7.Sample(samp7, ps.textCoordA);
float4 c8 = tile8.Sample(samp8, ps.textCoordA);
float4 fvBaseColor = c1;
float total = ps.w1+ps.w2+ps.w3+ps.w4+ps.w5+ps.w6+ps.w7+ps.w8;
if (total > 0.0)
fvBaseColor = c1 * ps.w1 +  c2 * ps.w2 +  c3 * ps.w3 +  c4 * ps.w4 +  c5 * ps.w5 +  c6 * ps.w6 +  c7 * ps.w7 +  c8 * ps.w8;
fvBaseColor.a = 0.0;
float NdotL = max(dot(n, normalize(float3(1000,-1000,1000))),0.0);
  float cut = 0.3;
  float shade = 0.85;
if (NdotL > cut + 0.05)
NdotL = 1.0;
else if (NdotL < cut)
NdotL = shade;
NdotL = ((NdotL - cut)*20)*(1.0-shade)+shade;
     NdotL = 1.0 - NdotL;
 float4 diffuse = float4(fvBaseColor.r-NdotL,fvBaseColor.g-NdotL,fvBaseColor.b-NdotL,1.0);
float4 colour1 = diffuse;
float len = length(ps.p-camera);
float start = 500.0;
float end = 700.0;
float4 fadeColor = float4(0.3,0.3,0.9,1.0);
if (len > start)
if (len > end)
colour1 = fadeColor;
colour1 = lerp(colour1,fadeColor,(len-start)/(end-start));
float4 cc2 = colour1;
cc2.a = 1.0;
 if (death == 1)
  float grey = (cc2.r+cc2.g+cc2.b)/3.0;
  cc2.r = grey;
  cc2.g = grey;
  cc2.b = grey;
 return cc2;
Here is the code that creates the texture. My game engine is written in Java but since you cant do directx in java directly I wrote my directx calls in c++). I create and concatenate all the mip levels in java before calling this c++ method. If the mipLevel is higher than one this method will only work for textures that has width and height values that is multiples of 2 I will improve that as soon as this problem is sorted out. This is probably the part that I'm the most unsure of. especially where I load all the mipmaps into the SUB_RESOURCE_DATA array.
struct Texture
ID3D11ShaderResourceView* textureView;
ID3D11DepthStencilView* depthStencilView;
ID3D11RenderTargetView* renderTargetView;
ID3D11SamplerState* sampler;
JNIEXPORT jint JNICALL Java_dmdx11_DmdxNative_createTexture(JNIEnv* env, jobject, jobject data, jint width, jint height, jint type,jint mipLevel)
Texture texture = Texture();
ID3D11Texture2D* pTexture;
if (type == 0)//color
D3D11_SHADER_RESOURCE_VIEW_DESC shaderResourceViewDesc;
D3D11_RENDER_TARGET_VIEW_DESC renderTargetViewDesc;
sTexDesc.Width = width;
sTexDesc.Height = height;
sTexDesc.MipLevels = mipLevel;
sTexDesc.ArraySize = 1;
sTexDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
sTexDesc.SampleDesc.Count = 1;
sTexDesc.SampleDesc.Quality = 0;
sTexDesc.Usage = D3D11_USAGE_IMMUTABLE;
sTexDesc.BindFlags = D3D11_BIND_SHADER_RESOURCE;
sTexDesc.CPUAccessFlags = 0;
sTexDesc.MiscFlags = 0;
int sofar = 0;
for (int i = 0; i < mipLevel; i++)
sSubData.pSysMem = (jbyte*)env->GetDirectBufferAddress(data) + sofar;
sSubData.SysMemPitch = (UINT)(width * 4);
sSubData.SysMemSlicePitch = (UINT)(width * height * 4);
sofar += (int)(width * height * 4);
width = width / 2;
height = height / 2;
hr = g_pd3dDevice->CreateTexture2D(&sTexDesc, sSubData, &pTexture);
delete[] sSubData;
shaderResourceViewDesc.Format = sTexDesc.Format;
shaderResourceViewDesc.ViewDimension = D3D11_SRV_DIMENSION_TEXTURE2D;
shaderResourceViewDesc.Texture2D.MostDetailedMip = 0;
shaderResourceViewDesc.Texture2D.MipLevels = mipLevel;
g_pd3dDevice->CreateShaderResourceView(pTexture, &shaderResourceViewDesc, &texture.textureView);
D3D11_SAMPLER_DESC sampDesc;
ZeroMemory(&sampDesc, sizeof(sampDesc));
sampDesc.Filter = D3D11_FILTER_MIN_MAG_MIP_LINEAR;
sampDesc.AddressU = D3D11_TEXTURE_ADDRESS_WRAP;
sampDesc.AddressV = D3D11_TEXTURE_ADDRESS_WRAP;
sampDesc.AddressW = D3D11_TEXTURE_ADDRESS_WRAP;
sampDesc.ComparisonFunc = D3D11_COMPARISON_NEVER;
sampDesc.MinLOD = 0;
sampDesc.MaxLOD = D3D11_FLOAT32_MAX;
g_pd3dDevice->CreateSamplerState(&sampDesc, &texture.sampler);
If theres any more information needed please ask.
Thank you for your time ^^
Edited by Wilhelm van Huyssteen

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Also, and unrelated to your problem, because sampler states are fully decoupled from textures, you can do this:


float4 c1 = tile1.Sample(samp1, ps.textCoordA);
float4 c2 = tile2.Sample(samp1, ps.textCoordA);
float4 c3 = tile3.Sample(samp1, ps.textCoordA);
float4 c4 = tile4.Sample(samp1, ps.textCoordA);
float4 c5 = tile5.Sample(samp1, ps.textCoordA);
float4 c6 = tile6.Sample(samp1, ps.textCoordA);
float4 c7 = tile7.Sample(samp1, ps.textCoordA);
float4 c8 = tile8.Sample(samp1, ps.textCoordA);

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0 isn't a valid value for MaxAnisotropy; it needs to be between 1 and 16: http://msdn.microsoft.com/en-us/library/windows/desktop/ff476207%28v=vs.85%29.aspx
(Note that 1, not 0, is for anisotropic filtering disabled).
I suggest correcting this first, then see if the problems still happen.


This value is ignored in case the filter type is not anisotropic.

Appraently, 0 is indeed a valid value even if the filter type is anisotropic.

D3D11 ERROR: ID3D11Device::CreateSamplerState: MaxAnisotropy must be in the range [0 to 16].  20 specified. [ STATE_CREATION ERROR #226: CREATESAMPLERSTATE_INVALIDMAXANISOTROPY]

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So. since mhagain mentioned that gluBuild2DMipmaps uses a box filter as well I went back to my mipmap generation code and I discovered that (as part of some earlier testing/debugging) I commented out the line of code that averages the 4 nearest pixels together and instead replaced it with a line that that just uses the value of the top-left pixel and ignores the rest...


Undoing that bit of test code the directx version now renders perfectly. Feel kind of silly. Should probably take it easy with all the late night coding.


Thank you for your time.

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      When sampling a texture in a shader, the texture sampler was traditionally specified as separate object that was bound to the pipeline at run time or set as part of the texture object itself. However, in most cases it is known beforehand what kind of sampler will be used in the shader. Next-generation APIs expose new type of sampler called static sampler that can be initialized directly in the pipeline state. Diligent Engine exposes this functionality: when creating a shader, textures can be assigned static samplers. If static sampler is assigned, it will always be used instead of the one initialized in the texture shader resource view. To initialize static samplers, prepare an array of StaticSamplerDesc structures and initialize StaticSamplers and NumStaticSamplers members. Static samplers are more efficient and it is highly recommended to use them whenever possible. On older APIs, static samplers are emulated via generic sampler objects.
      The following is an example of shader initialization:
      ShaderCreationAttribs Attrs; Attrs.Desc.Name = "MyPixelShader"; Attrs.FilePath = "MyShaderFile.fx"; Attrs.SearchDirectories = "shaders;shaders\\inc;"; Attrs.EntryPoint = "MyPixelShader"; Attrs.Desc.ShaderType = SHADER_TYPE_PIXEL; Attrs.SourceLanguage = SHADER_SOURCE_LANGUAGE_HLSL; BasicShaderSourceStreamFactory BasicSSSFactory(Attrs.SearchDirectories); Attrs.pShaderSourceStreamFactory = &BasicSSSFactory; ShaderVariableDesc ShaderVars[] = {     {"g_StaticTexture", SHADER_VARIABLE_TYPE_STATIC},     {"g_MutableTexture", SHADER_VARIABLE_TYPE_MUTABLE},     {"g_DynamicTexture", SHADER_VARIABLE_TYPE_DYNAMIC} }; Attrs.Desc.VariableDesc = ShaderVars; Attrs.Desc.NumVariables = _countof(ShaderVars); Attrs.Desc.DefaultVariableType = SHADER_VARIABLE_TYPE_STATIC; StaticSamplerDesc StaticSampler; StaticSampler.Desc.MinFilter = FILTER_TYPE_LINEAR; StaticSampler.Desc.MagFilter = FILTER_TYPE_LINEAR; StaticSampler.Desc.MipFilter = FILTER_TYPE_LINEAR; StaticSampler.TextureName = "g_MutableTexture"; Attrs.Desc.NumStaticSamplers = 1; Attrs.Desc.StaticSamplers = &StaticSampler; ShaderMacroHelper Macros; Macros.AddShaderMacro("USE_SHADOWS", 1); Macros.AddShaderMacro("NUM_SHADOW_SAMPLES", 4); Macros.Finalize(); Attrs.Macros = Macros; RefCntAutoPtr<IShader> pShader; m_pDevice->CreateShader( Attrs, &pShader );
      Creating the Pipeline State Object
      After all required shaders are created, the rest of the fields of the PipelineStateDesc structure provide depth-stencil, rasterizer, and blend state descriptions, the number and format of render targets, input layout format, etc. For instance, rasterizer state can be described as follows:
      PipelineStateDesc PSODesc; RasterizerStateDesc &RasterizerDesc = PSODesc.GraphicsPipeline.RasterizerDesc; RasterizerDesc.FillMode = FILL_MODE_SOLID; RasterizerDesc.CullMode = CULL_MODE_NONE; RasterizerDesc.FrontCounterClockwise = True; RasterizerDesc.ScissorEnable = True; RasterizerDesc.AntialiasedLineEnable = False; Depth-stencil and blend states are defined in a similar fashion.
      Another important thing that pipeline state object encompasses is the input layout description that defines how inputs to the vertex shader, which is the very first shader stage, should be read from the memory. Input layout may define several vertex streams that contain values of different formats and sizes:
      // Define input layout InputLayoutDesc &Layout = PSODesc.GraphicsPipeline.InputLayout; LayoutElement TextLayoutElems[] = {     LayoutElement( 0, 0, 3, VT_FLOAT32, False ),     LayoutElement( 1, 0, 4, VT_UINT8, True ),     LayoutElement( 2, 0, 2, VT_FLOAT32, False ), }; Layout.LayoutElements = TextLayoutElems; Layout.NumElements = _countof( TextLayoutElems ); Finally, pipeline state defines primitive topology type. When all required members are initialized, a pipeline state object can be created by IRenderDevice::CreatePipelineState() method:
      // Define shader and primitive topology PSODesc.GraphicsPipeline.PrimitiveTopologyType = PRIMITIVE_TOPOLOGY_TYPE_TRIANGLE; PSODesc.GraphicsPipeline.pVS = pVertexShader; PSODesc.GraphicsPipeline.pPS = pPixelShader; PSODesc.Name = "My pipeline state"; m_pDev->CreatePipelineState(PSODesc, &m_pPSO); When PSO object is bound to the pipeline, the engine invokes all API-specific commands to set all states specified by the object. In case of Direct3D12 this maps directly to setting the D3D12 PSO object. In case of Direct3D11, this involves setting individual state objects (such as rasterizer and blend states), shaders, input layout etc. In case of OpenGL, this requires a number of fine-grain state tweaking calls. Diligent Engine keeps track of currently bound states and only calls functions to update these states that have actually changed.
      Binding Shader Resources
      Direct3D11 and OpenGL utilize fine-grain resource binding models, where an application binds individual buffers and textures to certain shader or program resource binding slots. Direct3D12 uses a very different approach, where resource descriptors are grouped into tables, and an application can bind all resources in the table at once by setting the table in the command list. Resource binding model in Diligent Engine is designed to leverage this new method. It introduces a new object called shader resource binding that encapsulates all resource bindings required for all shaders in a certain pipeline state. It also introduces the classification of shader variables based on the frequency of expected change that helps the engine group them into tables under the hood:
      Static variables (SHADER_VARIABLE_TYPE_STATIC) are variables that are expected to be set only once. They may not be changed once a resource is bound to the variable. Such variables are intended to hold global constants such as camera attributes or global light attributes constant buffers. Mutable variables (SHADER_VARIABLE_TYPE_MUTABLE) define resources that are expected to change on a per-material frequency. Examples may include diffuse textures, normal maps etc. Dynamic variables (SHADER_VARIABLE_TYPE_DYNAMIC) are expected to change frequently and randomly. Shader variable type must be specified during shader creation by populating an array of ShaderVariableDesc structures and initializing ShaderCreationAttribs::Desc::VariableDesc and ShaderCreationAttribs::Desc::NumVariables members (see example of shader creation above).
      Static variables cannot be changed once a resource is bound to the variable. They are bound directly to the shader object. For instance, a shadow map texture is not expected to change after it is created, so it can be bound directly to the shader:
      PixelShader->GetShaderVariable( "g_tex2DShadowMap" )->Set( pShadowMapSRV ); Mutable and dynamic variables are bound via a new Shader Resource Binding object (SRB) that is created by the pipeline state (IPipelineState::CreateShaderResourceBinding()):
      m_pPSO->CreateShaderResourceBinding(&m_pSRB); Note that an SRB is only compatible with the pipeline state it was created from. SRB object inherits all static bindings from shaders in the pipeline, but is not allowed to change them.
      Mutable resources can only be set once for every instance of a shader resource binding. Such resources are intended to define specific material properties. For instance, a diffuse texture for a specific material is not expected to change once the material is defined and can be set right after the SRB object has been created:
      m_pSRB->GetVariable(SHADER_TYPE_PIXEL, "tex2DDiffuse")->Set(pDiffuseTexSRV); In some cases it is necessary to bind a new resource to a variable every time a draw command is invoked. Such variables should be labeled as dynamic, which will allow setting them multiple times through the same SRB object:
      m_pSRB->GetVariable(SHADER_TYPE_VERTEX, "cbRandomAttribs")->Set(pRandomAttrsCB); Under the hood, the engine pre-allocates descriptor tables for static and mutable resources when an SRB objcet is created. Space for dynamic resources is dynamically allocated at run time. Static and mutable resources are thus more efficient and should be used whenever possible.
      As you can see, Diligent Engine does not expose low-level details of how resources are bound to shader variables. One reason for this is that these details are very different for various APIs. The other reason is that using low-level binding methods is extremely error-prone: it is very easy to forget to bind some resource, or bind incorrect resource such as bind a buffer to the variable that is in fact a texture, especially during shader development when everything changes fast. Diligent Engine instead relies on shader reflection system to automatically query the list of all shader variables. Grouping variables based on three types mentioned above allows the engine to create optimized layout and take heavy lifting of matching resources to API-specific resource location, register or descriptor in the table.
      This post gives more details about the resource binding model in Diligent Engine.
      Setting the Pipeline State and Committing Shader Resources
      Before any draw or compute command can be invoked, the pipeline state needs to be bound to the context:
      m_pContext->SetPipelineState(m_pPSO); Under the hood, the engine sets the internal PSO object in the command list or calls all the required native API functions to properly configure all pipeline stages.
      The next step is to bind all required shader resources to the GPU pipeline, which is accomplished by IDeviceContext::CommitShaderResources() method:
      m_pContext->CommitShaderResources(m_pSRB, COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES); The method takes a pointer to the shader resource binding object and makes all resources the object holds available for the shaders. In the case of D3D12, this only requires setting appropriate descriptor tables in the command list. For older APIs, this typically requires setting all resources individually.
      Next-generation APIs require the application to track the state of every resource and explicitly inform the system about all state transitions. For instance, if a texture was used as render target before, while the next draw command is going to use it as shader resource, a transition barrier needs to be executed. Diligent Engine does the heavy lifting of state tracking.  When CommitShaderResources() method is called with COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES flag, the engine commits and transitions resources to correct states at the same time. Note that transitioning resources does introduce some overhead. The engine tracks state of every resource and it will not issue the barrier if the state is already correct. But checking resource state is an overhead that can sometimes be avoided. The engine provides IDeviceContext::TransitionShaderResources() method that only transitions resources:
      m_pContext->TransitionShaderResources(m_pPSO, m_pSRB); In some scenarios it is more efficient to transition resources once and then only commit them.
      Invoking Draw Command
      The final step is to set states that are not part of the PSO, such as render targets, vertex and index buffers. Diligent Engine uses Direct3D11-syle API that is translated to other native API calls under the hood:
      ITextureView *pRTVs[] = {m_pRTV}; m_pContext->SetRenderTargets(_countof( pRTVs ), pRTVs, m_pDSV); // Clear render target and depth buffer const float zero[4] = {0, 0, 0, 0}; m_pContext->ClearRenderTarget(nullptr, zero); m_pContext->ClearDepthStencil(nullptr, CLEAR_DEPTH_FLAG, 1.f); // Set vertex and index buffers IBuffer *buffer[] = {m_pVertexBuffer}; Uint32 offsets[] = {0}; Uint32 strides[] = {sizeof(MyVertex)}; m_pContext->SetVertexBuffers(0, 1, buffer, strides, offsets, SET_VERTEX_BUFFERS_FLAG_RESET); m_pContext->SetIndexBuffer(m_pIndexBuffer, 0); Different native APIs use various set of function to execute draw commands depending on command details (if the command is indexed, instanced or both, what offsets in the source buffers are used etc.). For instance, there are 5 draw commands in Direct3D11 and more than 9 commands in OpenGL with something like glDrawElementsInstancedBaseVertexBaseInstance not uncommon. Diligent Engine hides all details with single IDeviceContext::Draw() method that takes takes DrawAttribs structure as an argument. The structure members define all attributes required to perform the command (primitive topology, number of vertices or indices, if draw call is indexed or not, if draw call is instanced or not, if draw call is indirect or not, etc.). For example:
      DrawAttribs attrs; attrs.IsIndexed = true; attrs.IndexType = VT_UINT16; attrs.NumIndices = 36; attrs.Topology = PRIMITIVE_TOPOLOGY_TRIANGLE_LIST; pContext->Draw(attrs); For compute commands, there is IDeviceContext::DispatchCompute() method that takes DispatchComputeAttribs structure that defines compute grid dimension.
      Source Code
      Full engine source code is available on GitHub and is free to use. The repository contains tutorials, sample applications, asteroids performance benchmark and an example Unity project that uses Diligent Engine in native plugin.
      Atmospheric scattering sample demonstrates how Diligent Engine can be used to implement various rendering tasks: loading textures from files, using complex shaders, rendering to multiple render targets, using compute shaders and unordered access views, etc.

      Asteroids performance benchmark is based on this demo developed by Intel. It renders 50,000 unique textured asteroids and allows comparing performance of Direct3D11 and Direct3D12 implementations. Every asteroid is a combination of one of 1000 unique meshes and one of 10 unique textures.

      Finally, there is an example project that shows how Diligent Engine can be integrated with Unity.

      Future Work
      The engine is under active development. It currently supports Windows desktop, Universal Windows, Linux, Android, MacOS, and iOS platforms. Direct3D11, Direct3D12, OpenGL/GLES backends are now feature complete. Vulkan backend is coming next, and Metal backend is in the plan.
    • By LifeArtist
      Good Evening,
      I want to make a 2D game which involves displaying some debug information. Especially for collision, enemy sights and so on ...
      First of I was thinking about all those shapes which I need will need for debugging purposes: circles, rectangles, lines, polygons.
      I am really stucked right now because of the fundamental question:
      Where do I store my vertices positions for each line (object)? Currently I am not using a model matrix because I am using orthographic projection and set the final position within the VBO. That means that if I add a new line I would have to expand the "points" array and re-upload (recall glBufferData) it every time. The other method would be to use a model matrix and a fixed vbo for a line but it would be also messy to exactly create a line from (0,0) to (100,20) calculating the rotation and scale to make it fit.
      If I proceed with option 1 "updating the array each frame" I was thinking of having 4 draw calls every frame for the lines vao, polygons vao and so on. 
      In addition to that I am planning to use some sort of ECS based architecture. So the other question would be:
      Should I treat those debug objects as entities/components?
      For me it would make sense to treat them as entities but that's creates a new issue with the previous array approach because it would have for example a transform and render component. A special render component for debug objects (no texture etc) ... For me the transform component is also just a matrix but how would I then define a line?
      Treating them as components would'nt be a good idea in my eyes because then I would always need an entity. Well entity is just an id !? So maybe its a component?
    • By QQemka
      Hello. I am coding a small thingy in my spare time. All i want to achieve is to load a heightmap (as the lowest possible walking terrain), some static meshes (elements of the environment) and a dynamic character (meaning i can move, collide with heightmap/static meshes and hold a varying item in a hand ). Got a bunch of questions, or rather problems i can't find solution to myself. Nearly all are deal with graphics/gpu, not the coding part. My c++ is on high enough level.
      Let's go:
      Heightmap - i obviously want it to be textured, size is hardcoded to 256x256 squares. I can't have one huge texture stretched over entire terrain cause every pixel would be enormous. Thats why i decided to use 2 specified textures. First will be a tileset consisting of 16 square tiles (u v range from 0 to 0.25 for first tile and so on) and second a 256x256 buffer with 0-15 value representing index of the tile from tileset for every heigtmap square. Problem is, how do i blend the edges nicely and make some computationally cheap changes so its not obvious there are only 16 tiles? Is it possible to generate such terrain with some existing program?
      Collisions - i want to use bounding sphere and aabb. But should i store them for a model or entity instance? Meaning i have 20 same trees spawned using the same tree model, but every entity got its own transformation (position, scale etc). Storing collision component per instance grats faster access + is precalculated and transformed (takes additional memory, but who cares?), so i stick with this, right? What should i do if object is dynamically rotated? The aabb is no longer aligned and calculating per vertex min/max everytime object rotates/scales is pretty expensive, right?
      Drawing aabb - problem similar to above (storing aabb data per instance or model). This time in my opinion per model is enough since every instance also does not have own vertex buffer but uses the shared one (so 20 trees share reference to one tree model). So rendering aabb is about taking the model's aabb, transforming with instance matrix and voila. What about aabb vertex buffer (this is more of a cosmetic question, just curious, bumped onto it in time of writing this). Is it better to make it as 8 points and index buffer (12 lines), or only 2 vertices with min/max x/y/z and having the shaders dynamically generate 6 other vertices and draw the box? Or maybe there should be just ONE 1x1x1 cube box template moved/scaled per entity?
      What if one model got a diffuse texture and a normal map, and other has only diffuse? Should i pass some bool flag to shader with that info, or just assume that my game supports only diffuse maps without fancy stuff?
      There were several more but i forgot/solved them at time of writing
      Thanks in advance
    • By RenanRR
      Hi All,
      I'm reading the tutorials from learnOpengl site (nice site) and I'm having a question on the camera (https://learnopengl.com/Getting-started/Camera).
      I always saw the camera being manipulated with the lookat, but in tutorial I saw the camera being changed through the MVP arrays, which do not seem to be camera, but rather the scene that changes:
      Vertex Shader:
      #version 330 core layout (location = 0) in vec3 aPos; layout (location = 1) in vec2 aTexCoord; out vec2 TexCoord; uniform mat4 model; uniform mat4 view; uniform mat4 projection; void main() { gl_Position = projection * view * model * vec4(aPos, 1.0f); TexCoord = vec2(aTexCoord.x, aTexCoord.y); } then, the matrix manipulated:
      ..... glm::mat4 projection = glm::perspective(glm::radians(fov), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f); ourShader.setMat4("projection", projection); .... glm::mat4 view = glm::lookAt(cameraPos, cameraPos + cameraFront, cameraUp); ourShader.setMat4("view", view); .... model = glm::rotate(model, glm::radians(angle), glm::vec3(1.0f, 0.3f, 0.5f)); ourShader.setMat4("model", model);  
      So, some doubts:
      - Why use it like that?
      - Is it okay to manipulate the camera that way?
      -in this way, are not the vertex's positions that changes instead of the camera?
      - I need to pass MVP to all shaders of object in my scenes ?
      What it seems, is that the camera stands still and the scenery that changes...
      it's right?
      Thank you
    • By dpadam450
      Sampling a floating point texture where the alpha channel holds 4-bytes of packed data into the float. I don't know how to cast the raw memory to treat it as an integer so I can perform bit-shifting operations.

      int rgbValue = int(textureSample.w);//4 bytes of data packed as color
      // algorithm might not be correct and endianness might need switching.
      vec3 extractedData = vec3(  rgbValue & 0xFF000000,  (rgbValue << 8) & 0xFF000000, (rgbValue << 16) & 0xFF000000);
      extractedData /= 255.0f;
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