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POGDI is not rendering, what am I doing wrong?
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copied!<p>I am trying to make a basic framework for graphics with GDI to make some minigames with. But GDI is not rendering anything at all, I just get a black client area, and I have no idea what I'm doing wrong.</p> <p>The following code is inside a game loop that is running constantly:</p> <pre><code>//render double buffered with GDI HDC frontBuffer = GetDC(m_hMainWnd); HDC backBuffer; HBITMAP bitmap; HBITMAP oldBitmap; backBuffer = CreateCompatibleDC(frontBuffer); bitmap = CreateCompatibleBitmap(frontBuffer, m_ClientWidth, m_ClientHeight); oldBitmap = (HBITMAP)SelectObject(backBuffer, bitmap); GDI->StartDrawing(backBuffer, m_ClientWidth, m_ClientHeight); //this basically selects pens and brushes etc Render(dRenderTime); //here I render some stuff GDI->StopDrawing(backBuffer); //selects old pens and brushes back //blit backbuffer to frontbuffer BitBlt(frontBuffer, 0, 0, m_ClientWidth, m_ClientHeight, backBuffer, 0, 0, SRCCOPY); SelectObject(backBuffer, oldBitmap); DeleteObject(bitmap); DeleteDC(backBuffer); ReleaseDC(m_hMainWnd, frontBuffer); } </code></pre> <p>What am I doing wrong here? Sorry if it's some stupid mistake, I am not good at all with windows programming.</p> <p>EDIT: additional code, as requested:</p> <pre><code>gdi.h #pragma once #include <Windows.h> #include "Macros.h" #include "Transform.h" #include "Text.h" #define GDI gdi::getInstance() class gdi { private: HPEN m_OldPen; HPEN m_Pen; HBRUSH m_OldBrush; HBRUSH m_Brush; HDC m_hdc; int m_DcWidth; int m_DcHeight; COLORREF m_Color; int m_LineWidth; DBlib::float3x3 m_Transform; gdi(); void Transform(int& x_out, int& y_out, const DBlib::float2& p) const; void Transform_NDC_To_WC(int& x_out, int& y_out, const DBlib::float2& p) const; void Transfrom_WC_To_NDC(DBlib::float2& p_out, int x, int y) const; public: ~gdi(); static gdi* getInstance(); void StartDrawing(HDC hdc, int dcwidth, int dcheight); void StopDrawing(HDC hdc); void SetColor(const DBlib::float3& col); void SetLineWidth(int width); void SetTransform(const DBlib::float3x3& transform); void DrawText(const DBlib::float2& p1, const std::tstring& s); void DrawLine(const DBlib::float2& p1, const DBlib::float2& p2); void DrawPolygon(const DBlib::float2* p, int size); void FillPolygon(const DBlib::float2* p, int size); }; </code></pre> <p>GDI.cpp</p> <pre><code>#include "gdi.h" gdi* gdi::getInstance() { static gdi instance; return &instance; } gdi::gdi() { m_hdc = NULL; m_OldPen = NULL; m_OldBrush = NULL; m_LineWidth = 1; m_Color = RGB(0,0,0); m_DcWidth = -1; m_DcHeight = -1; m_Transform.set_identity(); m_Pen = CreatePen(PS_SOLID,1,RGB(0,0,0)); m_Brush = CreateSolidBrush(RGB(255,255,255)); } gdi::~gdi() { if(m_Pen) DeleteObject(m_Pen); if(m_Brush) DeleteObject(m_Brush); } void gdi::StartDrawing(HDC hdc, int dcwidth, int dcheight) { m_hdc = hdc; m_DcWidth = dcwidth; m_DcHeight = dcheight; m_OldPen = (HPEN)SelectObject(hdc, m_Pen); m_OldBrush = (HBRUSH)SelectObject(hdc, m_Brush); } void gdi::StopDrawing(HDC hdc) { SelectObject(hdc, m_OldPen); SelectObject(hdc, m_OldBrush); m_hdc = NULL; m_DcWidth = -1; m_DcHeight = -1; m_OldPen = NULL; m_OldBrush = NULL; } void gdi::SetColor(const DBlib::float3& col) { int r = static_cast<int>(DBlib::clamp(col.x*255.0f, 0.0f, 255.0f)); int g = static_cast<int>(DBlib::clamp(col.y*255.0f, 0.0f, 255.0f)); int b = static_cast<int>(DBlib::clamp(col.z*255.0f, 0.0f, 255.0f)); m_Color = RGB(r,g,b); SetTextColor(m_hdc, m_Color); if(m_Pen) DeleteObject(m_Pen); if(m_Brush) DeleteObject(m_Brush); m_Pen= CreatePen(PS_SOLID, m_LineWidth, m_Color); m_Brush= CreateSolidBrush(m_Color); } void gdi::SetLineWidth(int width) { m_LineWidth = width; if(m_Pen) DeleteObject(m_Pen); m_Pen= CreatePen(PS_SOLID, m_LineWidth, m_Color); } void gdi::SetTransform(const DBlib::float3x3& transform) { m_Transform = transform; } void gdi::Transform_NDC_To_WC(int& x_out, int& y_out, const DBlib::float2& p) const { x_out = static_cast<int>((p.x+1.0f)*(static_cast<float>(m_DcWidth)/2.0f)); y_out = m_DcHeight - static_cast<int>((p.y+1.0f)*(static_cast<float>(m_DcHeight)/2.0f)); } void gdi::Transfrom_WC_To_NDC(DBlib::float2& p_out, int x, int y) const { p_out.x = static_cast<float>(x)*2.0f/static_cast<float>(m_DcWidth) - 1.0f; p_out.y = -(static_cast<float>(y)*2.0f/static_cast<float>(m_DcHeight) - 1.0f); } void gdi::Transform(int& x_out, int& y_out, const DBlib::float2& p) const { Transform_NDC_To_WC(x_out, y_out, p*m_Transform); } void gdi::DrawText(const DBlib::float2& pos, const std::tstring& s) { int x,y; Transform(x,y,pos); TextOut(m_hdc, x, y, s.c_str(), (int)s.size()); } void gdi::DrawLine(const DBlib::float2& p1, const DBlib::float2& p2) { int x1,y1,x2,y2; Transform(x1,y1,p1); Transform(x2,y2,p2); MoveToEx(m_hdc, x1, y1, NULL); LineTo(m_hdc, x2, y2); } void gdi::DrawPolygon(const DBlib::float2* p, int size) { int* x = new int[size]; int* y = new int[size]; for(int i=0; i<size; ++i) { Transform(x[i],y[i],*(p+i)); } for(int i=0; i<size; ++i) { MoveToEx(m_hdc, x[i], y[i], NULL); LineTo(m_hdc, x[(i+1)%size], y[(i+1)%size]); } delete[] x; delete[] y; } void gdi::FillPolygon(const DBlib::float2* p, int size) { int* x = new int[size]; int* y = new int[size]; POINT* pts = new POINT[size]; for(int i=0; i<size; ++i) { Transform(x[i],y[i],*(p+i)); pts[i].x = static_cast<LONG>(x[i]); pts[i].y = static_cast<LONG>(y[i]); } Polygon(m_hdc, pts, size); delete[] x; delete[] y; delete[] pts; } </code></pre> <p>App.cpp - Render method definition</p> <pre><code>void App::Render(float dTime) { GDI->SetColor(DBlib::float3(1.0f,1.0f,1.0f)); GDI->SetLineWidth(50); GDI->DrawLine(DBlib::float2(-1.0f,-1.0f), DBlib::float2(1.0f,1.0f)); } </code></pre>

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