Backends: DX9: add programmable rendering pipeline implementation #3874

Demonese · 2021-03-04T06:03:59Z

Before

The old pull request #3844 is too messy, so I create a new pr to discuss.

I think this pull request won't be merged for a long time:

The master branch is under active development, but I may not be able to merge changes in the master branch in time
Direct3D9 is a 20-year-old API set, is very outdated, is used very rarely now
The performance improvement is not obvious (see below)

Thanks to @ocornut, bring us such an excellent GUI library 👍.

Why?

So why did I put so much effort into writing this implementation?

Current implementation need to convert the vertices. Yes, we can #define IMGUI_OVERRIDE_DRAWVERT_STRUCT_LAYOUT struct { ImVec2 pos; float z; ImVec2 uv; ImU32 col; };, but what about z? Can we ignore it whatever it is? Ok, we will also need to setup our custom MemAlloc and MemFree, but this is not very elegant.
My legecy project is using d3d9 programmable rendering pipeline (they still running on older devices).
Many online tutorials, blogs only touch fixed rendering pipeline of d3d9, or still using abandoned D3DX Effect library (in DirectX SDK). I share this implementation as a example to help others get rid of the legacy D3DX Effect library.

Features

Faster vertices copy without convertion (if IMGUI_USE_BGRA_PACKED_COLOR defined), and smaller vertex size result in faster upload
It can automatically enable support for programmable rendering pipelines without more consideration. (device compatible)
I didn't modify imgui_impl_dx9.h file. (API compatible)
It can compiled under C++98. (same as current implementation, no build issue)
It does not require other libraries (same as current implementation, only extra links to d3d9.lib, no MSVC link issue)

Test

Test code:

imconfig.h

#define IMGUI_USE_BGRA_PACKED_COLOR

imgui_impl_dx9.cpp

#include <stdio.h>
#include <Windows.h>
LARGE_INTEGER freq, t1, t2;
int timer = 0;
double times = 0.0f;

// Render function.
void ImGui_ImplDX9_RenderDrawData(ImDrawData* draw_data)
{
    ::QueryPerformanceCounter(&t1);

    ...

    ::QueryPerformanceCounter(&t2);
    times += (double)(t2.QuadPart - t1.QuadPart) * 1000000.0 / (double)freq.QuadPart;
    timer += 1;
    if ((timer % 60) == 0)
    {
        static char buffer[32];
        snprintf(buffer, 32, "%.3f\n", times / 60.0);
        OutputDebugStringA(buffer);
        times = 0.0f;
    }
}

bool ImGui_ImplDX9_Init(IDirect3DDevice9* device)
{
    ::QueryPerformanceFrequency(&freq);
    
    ...
}

main.cpp

...

ImDrawList* renderer = ImGui::GetBackgroundDrawList();
for (float x = 0.0f; x < 2048.0f; x += 8.0f)
{
    for (float y = 0.0f; y < 2048.0f; y += 8.0f)
    {
        renderer->AddRectFilled(ImVec2(x, y), ImVec2(x + 4.0f, y + 4.0f), IM_COL32(255, 255, 255, 128), 2.0f, 64);
    }
}

...

Build on Release config, running result:

Fixed rendering pipeline
Programmable rendering pipeline

Submitting the contents != rendering. Present is the best way to guarantee everything has been fully processed.

For those who need this...

You are free to merge this pr into your own fork. This implementation is already working on our old devices, although I didn't do a whole lot of testing.
But, anyway, I don't guarantee it's bug-free. If you have any questions, feel free to leave a comment.

ocornut · 2021-03-04T07:10:51Z

Thanks for the cleaned up PR and explanation! I am very surprised the fps is so low. Are you running on a very old computer? I would expect to get 1000+ fps on most machines. Printing to system console is slow you can remove this before checking the framerate.

Demonese · 2021-03-04T07:35:16Z

I am very surprised the fps is so low. Are you running on a very old computer? I would expect to get 1000+ fps on most machines. Printing to system console is slow you can remove this before checking the framerate.

65536 white rects & Intel integrated graphics card (awesome), cause low fps.
Our project using ImDrawList even more heavily, so I have to pay attention to the performance penalty of vertex conversions.

This is the normal FPS:

Demonese · 2021-11-14T12:00:14Z

Reorganized the code.
Now the newly inserted code is easier to recognize.

However, some duplicate codes have also been generated, and I am still thinking about how to solve it.

ocornut

Hello,

As you intuited, I'm not yet sure this can be merged because it seems rather esoteric, but I am glad this exist and I would encourage to further tweak it. The suggestions I posted here are to facilitate the likehood of merging.

ocornut · 2022-11-10T16:07:47Z

backends/imgui_impl_dx9.cpp

@@ -46,6 +46,11 @@ struct ImGui_ImplDX9_Data
    int                         VertexBufferSize;
    int                         IndexBufferSize;

+    IDirect3DVertexDeclaration9* pInputLayout;


Suggesting to add a comment at the top of those 4 fields, e.g. // Support for Shader Pipeline mode (rare).
Move the bool at the top of this 4 variables block.

I have moved the variable position and added comments. It may be surprising that the number of devices supporting shader model 2 is very large, so I didn't use (rare), this should be acceptable.

backends/imgui_impl_dx9.cpp

ocornut · 2022-11-10T16:10:27Z

backends/imgui_impl_dx9.cpp

+        // HLSL source code
+        /*
+            float4x4 mvp : register(c0);
+


Suggest compacting the source code a little, remove empty lines, compact structures into one-liner.
The reasoning is to make this "optional" feature of DX9 backend not takes too much visibility in the source file, making it more likely to be mergeable.

ok, I deleted redundant empty lines

ocornut · 2022-11-10T16:12:28Z

backends/imgui_impl_dx9.cpp

+        CODE(43,54,41,42),
+        CODE(1C,00,00,00),
+        CODE(4B,00,00,00),
+        CODE(00,02,FE,FF),


Suggest removing the macros and using raw 0xXX data, with 16-bytes per lines. This will reduce the line count by 4 and remove a subtle layer of complexity.

CODE(00,02,FE,FF), CODE(FE,FF,1E,00), CODE(43,54,41,42), CODE(1C,00,00,00),

into

0x00, 0x02, 0xFE, 0xFF, 0xFE, 0xFF, 0x1E, 0x00, 0x43, 0x54, 0x41, 0x42, 0x1C, 0x00, 0x00, 0x00,

Suggest adding a comment with an explicit command-line to turn the shader source into binary data.
I realize that MAYBE the output of that compiler is to output CODE(XX,XX,XX,XX) but as it is unlikely to be rebuild (our other shaders have stayed stables for many years) this is mostly as reference.

I finally decided to put them on the same line, and do not use hex, this helps reduce the number of source code characters (hex requires at least 3 characters, while decimal requires at least only 1)

ocornut · 2022-11-10T16:14:38Z

backends/imgui_impl_dx9.cpp

+
+    IDirect3DDevice9* ctx = bd->pd3dDevice;
+
+    // Setup orthographic projection matrix


Could this function call regular ImGui_ImplDX9_SetRenderState() and then add the extra stuff afterwise?

ocornut · 2022-11-10T16:16:12Z

backends/imgui_impl_dx9.cpp

@@ -143,6 +577,9 @@ static void ImGui_ImplDX9_SetupRenderState(ImDrawData* draw_data)
 // Render function.
 void ImGui_ImplDX9_RenderDrawData(ImDrawData* draw_data)
 {
+    if (ImGui_ImplDX9_Shader_RenderDrawData(draw_data))
+        return;
+


I think the bd->IsShaderPipeline test can be performed here, and the sub-function asserts on that value. Makes the flow more obvious.

This is really better. I have modified it

ocornut added the backends label Mar 4, 2021

Demonese force-pushed the imgui_impl_d3d9_shader branch 2 times, most recently from e662ed4 to 7716489 Compare March 11, 2021 14:24

Demonese force-pushed the imgui_impl_d3d9_shader branch 3 times, most recently from dfecb73 to 7229327 Compare March 19, 2021 01:54

Demonese force-pushed the imgui_impl_d3d9_shader branch from 7229327 to c813210 Compare April 29, 2021 05:15

Demonese force-pushed the imgui_impl_d3d9_shader branch from c813210 to e9e77fb Compare May 25, 2021 06:27

ocornut force-pushed the master branch 2 times, most recently from 0c1e5bd to bb6a60b Compare August 27, 2021 19:10

Demonese force-pushed the imgui_impl_d3d9_shader branch from e9e77fb to 31ad115 Compare November 14, 2021 08:26

ocornut force-pushed the master branch 2 times, most recently from 8b83e0a to d735066 Compare December 13, 2021 11:31

ocornut force-pushed the master branch from 9aa764c to b0a6cd6 Compare January 3, 2022 20:47

ocornut force-pushed the master branch 2 times, most recently from b3b85d8 to 0755767 Compare January 17, 2022 14:21

ocornut force-pushed the master branch 3 times, most recently from c817acb to 8d39063 Compare February 15, 2022 16:25

ocornut force-pushed the master branch from 8e10b7a to fc203c7 Compare April 12, 2022 13:30

Demonese force-pushed the imgui_impl_d3d9_shader branch 2 times, most recently from bd21d4f to 717adfa Compare September 23, 2022 07:29

ocornut reviewed Nov 10, 2022

View reviewed changes

Demonese force-pushed the imgui_impl_d3d9_shader branch 3 times, most recently from d83a52c to 702e1d5 Compare November 15, 2022 17:49

ocornut force-pushed the master branch from 14d4b36 to c9aef16 Compare January 2, 2023 15:25

ocornut force-pushed the master branch from 4812791 to fac19e1 Compare February 7, 2023 18:29

Demonese force-pushed the imgui_impl_d3d9_shader branch from 702e1d5 to 86e5977 Compare February 15, 2023 15:20

Demonese force-pushed the imgui_impl_d3d9_shader branch from 86e5977 to fc8094e Compare March 18, 2023 14:28

Demonese force-pushed the imgui_impl_d3d9_shader branch from fc8094e to a093e5a Compare June 20, 2023 02:37

Kuanlan added 2 commits July 5, 2023 10:34

Backends: DX9: programmable rendering pipeline

bdf517c

Backends: DX9: less duplicate code

1424f6b

Demonese force-pushed the imgui_impl_d3d9_shader branch from a093e5a to 1424f6b Compare July 5, 2023 02:35

ocornut mentioned this pull request Nov 3, 2023

Custom DX9: backend: certain Widgets do not get clipped inside the Window properly #6980

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Backends: DX9: add programmable rendering pipeline implementation #3874

Backends: DX9: add programmable rendering pipeline implementation #3874

Demonese commented Mar 4, 2021 •

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		IDirect3DDevice9* ctx = bd->pd3dDevice;

		// Setup orthographic projection matrix

Backends: DX9: add programmable rendering pipeline implementation #3874

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Backends: DX9: add programmable rendering pipeline implementation #3874

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Demonese commented Mar 4, 2021 • edited Loading

Before

Why?

Features

Test

For those who need this...

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