// dear imgui: Renderer for DirectX9
// This needs to be used along with a Platform Binding (e.g. Win32)

// Implemented features:
//  [X] Renderer: User texture binding. Use 'LPDIRECT3DTEXTURE9' as ImTextureID. Read the FAQ about ImTextureID in imgui.cpp.

// You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this.
// If you are new to dear imgui, read examples/README.txt and read the documentation at the top of imgui.cpp.
// https://github.com/ocornut/imgui

// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
//  2019-01-16: Misc: Disabled fog before drawing UI's. Fixes issue #2288.
//  2018-11-30: Misc: Setting up io.BackendRendererName so it can be displayed in the About Window.
//  2018-06-08: Misc: Extracted imgui_impl_dx9.cpp/.h away from the old combined DX9+Win32 example.
//  2018-06-08: DirectX9: Use draw_data->DisplayPos and draw_data->DisplaySize to setup projection matrix and clipping rectangle.
//  2018-05-07: Render: Saving/restoring Transform because they don't seem to be included in the StateBlock. Setting shading mode to Gouraud.
//  2018-02-16: Misc: Obsoleted the io.RenderDrawListsFn callback and exposed ImGui_ImplDX9_RenderDrawData() in the .h file so you can call it yourself.
//  2018-02-06: Misc: Removed call to ui::Shutdown() which is not available from 1.60 WIP, user needs to call CreateContext/DestroyContext themselves.

#include "imgui.h"
#include "imgui_impl_dx9.h"

// DirectX
#include <d3d9.h>
#define DIRECTINPUT_VERSION 0x0800
#include <dinput.h>

// DirectX data
static LPDIRECT3DDEVICE9        g_pd3dDevice = NULL;
static LPDIRECT3DVERTEXBUFFER9  g_pVB = NULL;
static LPDIRECT3DINDEXBUFFER9   g_pIB = NULL;
static LPDIRECT3DTEXTURE9       g_FontTexture = NULL;
static int                      g_VertexBufferSize = 5000, g_IndexBufferSize = 10000;

struct CUSTOMVERTEX
{
	float    pos[3];
	D3DCOLOR col;
	float    uv[2];
};
#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZ|D3DFVF_DIFFUSE|D3DFVF_TEX1)

// Render function.
// (this used to be set in io.RenderDrawListsFn and called by ui::Render(), but you can now call this directly from your main loop)
void ImGui_ImplDX9_RenderDrawData(ImDrawData* draw_data)
{
	// Avoid rendering when minimized
	if (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f)
		return;

	// Create and grow buffers if needed
	if (!g_pVB || g_VertexBufferSize < draw_data->TotalVtxCount)
	{
		if (g_pVB) { g_pVB->Release(); g_pVB = NULL; }
		g_VertexBufferSize = draw_data->TotalVtxCount + 5000;
		if (g_pd3dDevice->CreateVertexBuffer(g_VertexBufferSize * sizeof(CUSTOMVERTEX), D3DUSAGE_DYNAMIC | D3DUSAGE_WRITEONLY, D3DFVF_CUSTOMVERTEX, D3DPOOL_DEFAULT, &g_pVB, NULL) < 0)
			return;
	}
	if (!g_pIB || g_IndexBufferSize < draw_data->TotalIdxCount)
	{
		if (g_pIB) { g_pIB->Release(); g_pIB = NULL; }
		g_IndexBufferSize = draw_data->TotalIdxCount + 10000;
		if (g_pd3dDevice->CreateIndexBuffer(g_IndexBufferSize * sizeof(ImDrawIdx), D3DUSAGE_DYNAMIC | D3DUSAGE_WRITEONLY, sizeof(ImDrawIdx) == 2 ? D3DFMT_INDEX16 : D3DFMT_INDEX32, D3DPOOL_DEFAULT, &g_pIB, NULL) < 0)
			return;
	}

	// Backup the DX9 state
	IDirect3DStateBlock9* d3d9_state_block = NULL;
	if (g_pd3dDevice->CreateStateBlock(D3DSBT_PIXELSTATE, &d3d9_state_block) < 0)
		return;

	// Backup the DX9 transform (DX9 documentation suggests that it is included in the StateBlock but it doesn't appear to)
	D3DMATRIX last_world, last_view, last_projection;
	g_pd3dDevice->GetTransform(D3DTS_WORLD, &last_world);
	g_pd3dDevice->GetTransform(D3DTS_VIEW, &last_view);
	g_pd3dDevice->GetTransform(D3DTS_PROJECTION, &last_projection);

	// Copy and convert all vertices into a single contiguous buffer, convert colors to DX9 default format.
	// FIXME-OPT: This is a waste of resource, the ideal is to use imconfig.h and
	//  1) to avoid repacking colors:   #define IMGUI_USE_BGRA_PACKED_COLOR
	//  2) to avoid repacking vertices: #define IMGUI_OVERRIDE_DRAWVERT_STRUCT_LAYOUT struct ImDrawVert { ImVec2 pos; float z; ImU32 col; ImVec2 uv; }
	CUSTOMVERTEX* vtx_dst;
	ImDrawIdx* idx_dst;
	if (g_pVB->Lock(0, (UINT)(draw_data->TotalVtxCount * sizeof(CUSTOMVERTEX)), (void**)&vtx_dst, D3DLOCK_DISCARD) < 0)
		return;
	if (g_pIB->Lock(0, (UINT)(draw_data->TotalIdxCount * sizeof(ImDrawIdx)), (void**)&idx_dst, D3DLOCK_DISCARD) < 0)
		return;
	for (int n = 0; n < draw_data->CmdListsCount; n++)
	{
		const ImDrawList* cmd_list = draw_data->CmdLists[n];
		const ImDrawVert* vtx_src = cmd_list->VtxBuffer.Data;
		for (int i = 0; i < cmd_list->VtxBuffer.Size; i++)
		{
			vtx_dst->pos[0] = vtx_src->pos.x;
			vtx_dst->pos[1] = vtx_src->pos.y;
			vtx_dst->pos[2] = 0.0f;
			vtx_dst->col = (vtx_src->col & 0xFF00FF00) | ((vtx_src->col & 0xFF0000) >> 16) | ((vtx_src->col & 0xFF) << 16);     // RGBA --> ARGB for DirectX9
			vtx_dst->uv[0] = vtx_src->uv.x;
			vtx_dst->uv[1] = vtx_src->uv.y;
			vtx_dst++;
			vtx_src++;
		}
		memcpy(idx_dst, cmd_list->IdxBuffer.Data, cmd_list->IdxBuffer.Size * sizeof(ImDrawIdx));
		idx_dst += cmd_list->IdxBuffer.Size;
	}
	g_pVB->Unlock();
	g_pIB->Unlock();
	g_pd3dDevice->SetStreamSource(0, g_pVB, 0, sizeof(CUSTOMVERTEX));
	g_pd3dDevice->SetIndices(g_pIB);
	g_pd3dDevice->SetFVF(D3DFVF_CUSTOMVERTEX);

	// Setup viewport
	D3DVIEWPORT9 vp;
	vp.X = vp.Y = 0;
	vp.Width = (DWORD)draw_data->DisplaySize.x;
	vp.Height = (DWORD)draw_data->DisplaySize.y;
	vp.MinZ = 0.0f;
	vp.MaxZ = 1.0f;
	g_pd3dDevice->SetViewport(&vp);

	// Setup render state: fixed-pipeline, alpha-blending, no face culling, no depth testing, shade mode (for gradient)
	g_pd3dDevice->SetPixelShader(NULL);
	g_pd3dDevice->SetVertexShader(NULL);
	g_pd3dDevice->SetRenderState(D3DRS_CULLMODE, D3DCULL_NONE);
	g_pd3dDevice->SetRenderState(D3DRS_LIGHTING, false);
	g_pd3dDevice->SetRenderState(D3DRS_ZENABLE, false);
	g_pd3dDevice->SetRenderState(D3DRS_ALPHABLENDENABLE, true);
	g_pd3dDevice->SetRenderState(D3DRS_ALPHATESTENABLE, false);
	g_pd3dDevice->SetRenderState(D3DRS_BLENDOP, D3DBLENDOP_ADD);
	g_pd3dDevice->SetRenderState(D3DRS_SRCBLEND, D3DBLEND_SRCALPHA);
	g_pd3dDevice->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_INVSRCALPHA);
	g_pd3dDevice->SetRenderState(D3DRS_SCISSORTESTENABLE, true);
	g_pd3dDevice->SetRenderState(D3DRS_SHADEMODE, D3DSHADE_GOURAUD);
	g_pd3dDevice->SetRenderState(D3DRS_FOGENABLE, false);
	g_pd3dDevice->SetTextureStageState(0, D3DTSS_COLOROP, D3DTOP_MODULATE);
	g_pd3dDevice->SetTextureStageState(0, D3DTSS_COLORARG1, D3DTA_TEXTURE);
	g_pd3dDevice->SetTextureStageState(0, D3DTSS_COLORARG2, D3DTA_DIFFUSE);
	g_pd3dDevice->SetTextureStageState(0, D3DTSS_ALPHAOP, D3DTOP_MODULATE);
	g_pd3dDevice->SetTextureStageState(0, D3DTSS_ALPHAARG1, D3DTA_TEXTURE);
	g_pd3dDevice->SetTextureStageState(0, D3DTSS_ALPHAARG2, D3DTA_DIFFUSE);
	g_pd3dDevice->SetSamplerState(0, D3DSAMP_MINFILTER, D3DTEXF_LINEAR);
	g_pd3dDevice->SetSamplerState(0, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR);

	// Setup orthographic projection matrix
	// Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right).
	// Being agnostic of whether <d3dx9.h> or <DirectXMath.h> can be used, we aren't relying on D3DXMatrixIdentity()/D3DXMatrixOrthoOffCenterLH() or DirectX::XMMatrixIdentity()/DirectX::XMMatrixOrthographicOffCenterLH()
	{
		float L = draw_data->DisplayPos.x + 0.5f;
		float R = draw_data->DisplayPos.x + draw_data->DisplaySize.x + 0.5f;
		float T = draw_data->DisplayPos.y + 0.5f;
		float B = draw_data->DisplayPos.y + draw_data->DisplaySize.y + 0.5f;
		D3DMATRIX mat_identity = { { { 1.0f, 0.0f, 0.0f, 0.0f,  0.0f, 1.0f, 0.0f, 0.0f,  0.0f, 0.0f, 1.0f, 0.0f,  0.0f, 0.0f, 0.0f, 1.0f } } };
		D3DMATRIX mat_projection =
		{ { {
			2.0f / (R - L),   0.0f,         0.0f,  0.0f,
			0.0f,         2.0f / (T - B),   0.0f,  0.0f,
			0.0f,         0.0f,         0.5f,  0.0f,
			(L + R) / (L - R),  (T + B) / (B - T),  0.5f,  1.0f
		} } };
		g_pd3dDevice->SetTransform(D3DTS_WORLD, &mat_identity);
		g_pd3dDevice->SetTransform(D3DTS_VIEW, &mat_identity);
		g_pd3dDevice->SetTransform(D3DTS_PROJECTION, &mat_projection);
	}

	// Render command lists
	int vtx_offset = 0;
	int idx_offset = 0;
	ImVec2 clip_off = draw_data->DisplayPos;
	for (int n = 0; n < draw_data->CmdListsCount; n++)
	{
		const ImDrawList* cmd_list = draw_data->CmdLists[n];
		for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
		{
			const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
			if (pcmd->UserCallback)
			{
				pcmd->UserCallback(cmd_list, pcmd);
			}
			else
			{
				const RECT r = { (LONG)(pcmd->ClipRect.x - clip_off.x), (LONG)(pcmd->ClipRect.y - clip_off.y), (LONG)(pcmd->ClipRect.z - clip_off.x), (LONG)(pcmd->ClipRect.w - clip_off.y) };
				const LPDIRECT3DTEXTURE9 texture = (LPDIRECT3DTEXTURE9)pcmd->TextureId;
				g_pd3dDevice->SetTexture(0, texture);
				g_pd3dDevice->SetScissorRect(&r);
				g_pd3dDevice->DrawIndexedPrimitive(D3DPT_TRIANGLELIST, vtx_offset, 0, (UINT)cmd_list->VtxBuffer.Size, idx_offset, pcmd->ElemCount / 3);
			}
			idx_offset += pcmd->ElemCount;
		}
		vtx_offset += cmd_list->VtxBuffer.Size;
	}

	// Restore the DX9 transform
	g_pd3dDevice->SetTransform(D3DTS_WORLD, &last_world);
	g_pd3dDevice->SetTransform(D3DTS_VIEW, &last_view);
	g_pd3dDevice->SetTransform(D3DTS_PROJECTION, &last_projection);

	// Restore the DX9 state
	d3d9_state_block->Apply();
	d3d9_state_block->Release();
}

bool ImGui_ImplDX9_Init(IDirect3DDevice9* device)
{
	ImGuiIO& io = ui::GetIO();
	io.BackendRendererName = "imgui_impl_dx9";

	g_pd3dDevice = device;
	return true;
}

void ImGui_ImplDX9_Shutdown()
{
	ImGui_ImplDX9_InvalidateDeviceObjects();
	g_pd3dDevice = NULL;
}

static bool ImGui_ImplDX9_CreateFontsTexture()
{
	// Build texture atlas
	ImGuiIO& io = ui::GetIO();
	unsigned char* pixels;
	int width, height, bytes_per_pixel;
	io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height, &bytes_per_pixel);

	// Upload texture to graphics system
	g_FontTexture = NULL;
	if (g_pd3dDevice->CreateTexture(width, height, 1, D3DUSAGE_DYNAMIC, D3DFMT_A8R8G8B8, D3DPOOL_DEFAULT, &g_FontTexture, NULL) < 0)
		return false;
	D3DLOCKED_RECT tex_locked_rect;
	if (g_FontTexture->LockRect(0, &tex_locked_rect, NULL, 0) != D3D_OK)
		return false;
	for (int y = 0; y < height; y++)
		memcpy((unsigned char *)tex_locked_rect.pBits + tex_locked_rect.Pitch * y, pixels + (width * bytes_per_pixel) * y, (width * bytes_per_pixel));
	g_FontTexture->UnlockRect(0);

	// Store our identifier
	io.Fonts->TexID = (ImTextureID)g_FontTexture;

	return true;
}

bool ImGui_ImplDX9_CreateDeviceObjects()
{
	if (!g_pd3dDevice)
		return false;
	if (!ImGui_ImplDX9_CreateFontsTexture())
		return false;
	return true;
}

void ImGui_ImplDX9_InvalidateDeviceObjects()
{
	if (!g_pd3dDevice)
		return;
	if (g_pVB)
	{
		g_pVB->Release();
		g_pVB = NULL;
	}
	if (g_pIB)
	{
		g_pIB->Release();
		g_pIB = NULL;
	}

	// At this point note that we set ui::GetIO().Fonts->TexID to be == g_FontTexture, so clear both.
	ImGuiIO& io = ui::GetIO();
	IM_ASSERT(g_FontTexture == io.Fonts->TexID);
	if (g_FontTexture)
		g_FontTexture->Release();
	g_FontTexture = NULL;
	io.Fonts->TexID = NULL;
}

void ImGui_ImplDX9_NewFrame()
{
	if (!g_FontTexture)
		ImGui_ImplDX9_CreateDeviceObjects();
}
