From 56bc6c7ba6b8edf7afe530e22e15077a5be917ef Mon Sep 17 00:00:00 2001
From: Nico de Poel <ndepoel@gmail.com>
Date: Wed, 21 Apr 2021 15:12:44 +0200
Subject: [PATCH] Added empty stub implementations of OpenGL calls used by
 Quake, as an alternative way of removing the dependencies on SDL & OpenGL

---
 engine/UniQuake/stub/stub_opengl.c            | 289 ++++++++++++++++++
 engine/Windows/VisualStudio/uniquake.vcxproj  |   5 +-
 .../VisualStudio/uniquake.vcxproj.filters     |   6 +
 3 files changed, 298 insertions(+), 2 deletions(-)
 create mode 100644 engine/UniQuake/stub/stub_opengl.c

diff --git a/engine/UniQuake/stub/stub_opengl.c b/engine/UniQuake/stub/stub_opengl.c
new file mode 100644
index 0000000..fb1f082
--- /dev/null
+++ b/engine/UniQuake/stub/stub_opengl.c
@@ -0,0 +1,289 @@
+#ifndef USE_OPENGL
+#define BUILD_GL32
+#include "SDL_opengl.h"
+
+#if !defined(__WIN32__)
+#undef GLAPI
+#define GLAPI
+#endif
+
+GLAPI void GLAPIENTRY glBegin(GLenum mode)
+{
+}
+
+GLAPI void GLAPIENTRY glEnd(void)
+{
+}
+
+GLAPI void GLAPIENTRY glEnable(GLenum cap)
+{
+}
+
+GLAPI void GLAPIENTRY glDisable(GLenum cap)
+{
+}
+
+GLAPI void GLAPIENTRY glBlendFunc(GLenum sfactor, GLenum dfactor)
+{
+}
+
+GLAPI void GLAPIENTRY glMatrixMode(GLenum mode)
+{
+}
+
+GLAPI void GLAPIENTRY glOrtho(GLdouble left, GLdouble right,
+	GLdouble bottom, GLdouble top,
+	GLdouble near_val, GLdouble far_val)
+{
+}
+
+GLAPI void GLAPIENTRY glFrustum(GLdouble left, GLdouble right,
+	GLdouble bottom, GLdouble top,
+	GLdouble near_val, GLdouble far_val)
+{
+}
+
+GLAPI void GLAPIENTRY glViewport(GLint x, GLint y,
+	GLsizei width, GLsizei height)
+{
+}
+
+GLAPI void GLAPIENTRY glPushMatrix(void)
+{
+}
+
+GLAPI void GLAPIENTRY glPopMatrix(void)
+{
+}
+
+GLAPI void GLAPIENTRY glLoadIdentity(void)
+{
+}
+
+GLAPI void GLAPIENTRY glMultMatrixf(const GLfloat *m)
+{
+}
+
+GLAPI void GLAPIENTRY glRotatef(GLfloat angle,
+	GLfloat x, GLfloat y, GLfloat z)
+{
+}
+
+GLAPI void GLAPIENTRY glScalef(GLfloat x, GLfloat y, GLfloat z)
+{
+}
+
+GLAPI void GLAPIENTRY glTranslatef(GLfloat x, GLfloat y, GLfloat z)
+{
+}
+
+GLAPI void GLAPIENTRY glVertex2f(GLfloat x, GLfloat y)
+{
+}
+
+GLAPI void GLAPIENTRY glVertex3f(GLfloat x, GLfloat y, GLfloat z)
+{
+}
+
+GLAPI void GLAPIENTRY glVertex3fv(const GLfloat *v)
+{
+}
+
+GLAPI void GLAPIENTRY glColor3f(GLfloat red, GLfloat green, GLfloat blue)
+{
+}
+
+GLAPI void GLAPIENTRY glColor3fv(const GLfloat *v)
+{
+}
+
+GLAPI void GLAPIENTRY glColor4f(GLfloat red, GLfloat green, GLfloat blue, GLfloat alpha)
+{
+}
+
+GLAPI void GLAPIENTRY glColor4fv(const GLfloat *v)
+{
+}
+
+GLAPI void GLAPIENTRY glColor4ubv(const GLubyte *v)
+{
+}
+
+GLAPI void GLAPIENTRY glTexCoord2f(GLfloat s, GLfloat t)
+{
+}
+
+GLAPI void GLAPIENTRY glTexEnvf(GLenum target, GLenum pname, GLfloat param)
+{
+}
+
+GLAPI void GLAPIENTRY glTexEnvi(GLenum target, GLenum pname, GLint param)
+{
+}
+
+GLAPI void GLAPIENTRY glFogf(GLenum pname, GLfloat param)
+{
+}
+
+GLAPI void GLAPIENTRY glFogi(GLenum pname, GLint param)
+{
+}
+
+GLAPI void GLAPIENTRY glFogfv(GLenum pname, const GLfloat *params)
+{
+}
+
+GLAPI void GLAPIENTRY glDepthFunc(GLenum func)
+{
+}
+
+GLAPI void GLAPIENTRY glDepthMask(GLboolean flag)
+{
+}
+
+GLAPI void GLAPIENTRY glDepthRange(GLclampd near_val, GLclampd far_val)
+{
+}
+
+GLAPI void GLAPIENTRY glShadeModel(GLenum mode)
+{
+}
+
+GLAPI void GLAPIENTRY glClearColor(GLclampf red, GLclampf green, GLclampf blue, GLclampf alpha)
+{
+}
+
+GLAPI void GLAPIENTRY glClear(GLbitfield mask)
+{
+}
+
+GLAPI void GLAPIENTRY glColorMask(GLboolean red, GLboolean green, GLboolean blue, GLboolean alpha)
+{
+}
+
+GLAPI void GLAPIENTRY glPolygonMode(GLenum face, GLenum mode)
+{
+}
+
+GLAPI void GLAPIENTRY glPolygonOffset(GLfloat factor, GLfloat units)
+{
+}
+
+GLAPI void GLAPIENTRY glFinish(void)
+{
+}
+
+GLAPI void GLAPIENTRY glStencilFunc(GLenum func, GLint ref, GLuint mask)
+{
+}
+
+GLAPI void GLAPIENTRY glStencilOp(GLenum fail, GLenum zfail, GLenum zpass)
+{
+}
+
+GLAPI void GLAPIENTRY glTexParameterf(GLenum target, GLenum pname, GLfloat param)
+{
+}
+
+GLAPI void GLAPIENTRY glTexParameteri(GLenum target, GLenum pname, GLint param)
+{
+}
+
+GLAPI void GLAPIENTRY glTexImage2D(GLenum target, GLint level,
+	GLint internalFormat,
+	GLsizei width, GLsizei height,
+	GLint border, GLenum format, GLenum type,
+	const GLvoid *pixels)
+{
+}
+
+GLAPI void GLAPIENTRY glGenTextures(GLsizei n, GLuint *textures)
+{
+	memset(textures, 0, sizeof(GLuint) * n);
+}
+
+GLAPI void GLAPIENTRY glDeleteTextures(GLsizei n, const GLuint *textures)
+{
+}
+
+GLAPI void GLAPIENTRY glBindTexture(GLenum target, GLuint texture)
+{
+}
+
+GLAPI void GLAPIENTRY glPixelStorei(GLenum pname, GLint param)
+{
+}
+
+GLAPI void GLAPIENTRY glReadPixels(GLint x, GLint y,
+	GLsizei width, GLsizei height,
+	GLenum format, GLenum type,
+	GLvoid *pixels)
+{
+	int stride, sz;
+	switch (format)
+	{
+	case GL_RGB:
+		stride = 3;
+		break;
+	case GL_RGBA:
+		stride = 4;
+		break;
+	default:
+		stride = 0;
+		break;
+	}
+
+	switch (type)
+	{
+	case GL_UNSIGNED_BYTE:
+		sz = sizeof(unsigned char);
+		break;
+	default:
+		sz = 0;
+		break;
+	}
+
+	memset(pixels, 0, width * height * sz * stride);
+}
+
+GLAPI void GLAPIENTRY glGetIntegerv(GLenum pname, GLint *params)
+{
+	*params = 0;
+}
+
+GLAPI void GLAPIENTRY glGetTexImage(GLenum target, GLint level,
+	GLenum format, GLenum type,
+	GLvoid *pixels)
+{
+	// No way to figure out texture dimensions from just these parameters, so ignore
+}
+
+GLAPI void GLAPIENTRY glCopyTexSubImage2D(GLenum target, GLint level,
+	GLint xoffset, GLint yoffset,
+	GLint x, GLint y,
+	GLsizei width, GLsizei height)
+{
+}
+
+GLAPI void GLAPIENTRY glHint(GLenum target, GLenum mode)
+{
+}
+
+GLAPI void GLAPIENTRY glDrawElements(GLenum mode, GLsizei count,
+	GLenum type, const GLvoid *indices)
+{
+}
+
+GLAPI void GLAPIENTRY glTexSubImage2D(GLenum target, GLint level,
+	GLint xoffset, GLint yoffset,
+	GLsizei width, GLsizei height,
+	GLenum format, GLenum type,
+	const GLvoid *pixels)
+{
+}
+
+GLAPI void GLAPIENTRY glScissor(GLint x, GLint y, GLsizei width, GLsizei height)
+{
+}
+
+#endif	// !USE_OPENGL
diff --git a/engine/Windows/VisualStudio/uniquake.vcxproj b/engine/Windows/VisualStudio/uniquake.vcxproj
index e35704a..e3a99f5 100644
--- a/engine/Windows/VisualStudio/uniquake.vcxproj
+++ b/engine/Windows/VisualStudio/uniquake.vcxproj
@@ -149,7 +149,7 @@
     <ClCompile>
       <Optimization>Disabled</Optimization>
       <AdditionalIncludeDirectories>..\SDL2\include;..\..\FMOD\inc;..\..\Quake;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>UNIQUAKE_EXPORTS;WIN32;_DEBUG;_WINDOWS;_CRT_NONSTDC_NO_DEPRECATE;_CRT_SECURE_NO_WARNINGS;USE_FMOD;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>UNIQUAKE_EXPORTS;WIN32;_DEBUG;_WINDOWS;_CRT_NONSTDC_NO_DEPRECATE;_CRT_SECURE_NO_WARNINGS;USE_FMOD;USE_SDL2;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <MinimalRebuild>true</MinimalRebuild>
       <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
       <RuntimeLibrary>MultiThreadedDebugDLL</RuntimeLibrary>
@@ -233,7 +233,7 @@ copy "$(SolutionDir)\..\SDL2\lib\*.dll" "$(TargetDir)"</Command>
     <ClCompile>
       <Optimization>Disabled</Optimization>
       <AdditionalIncludeDirectories>..\SDL2\include;..\..\FMOD\inc;..\..\Quake;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>UNIQUAKE_EXPORTS;WIN32;_DEBUG;_WINDOWS;_CRT_NONSTDC_NO_DEPRECATE;_CRT_SECURE_NO_WARNINGS;USE_FMOD;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>UNIQUAKE_EXPORTS;WIN32;_DEBUG;_WINDOWS;_CRT_NONSTDC_NO_DEPRECATE;_CRT_SECURE_NO_WARNINGS;USE_FMOD;USE_SDL2;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <MinimalRebuild>true</MinimalRebuild>
       <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
       <RuntimeLibrary>MultiThreadedDebugDLL</RuntimeLibrary>
@@ -363,6 +363,7 @@ copy "$(SolutionDir)\..\SDL2\lib64\*.dll" "$(TargetDir)"</Command>
     <ClCompile Include="..\..\Quake\world.c" />
     <ClCompile Include="..\..\Quake\zone.c" />
     <ClCompile Include="..\..\UniQuake\gl_uniquake.c" />
+    <ClCompile Include="..\..\UniQuake\stub\stub_opengl.c" />
     <ClCompile Include="..\..\UniQuake\sys_uniquake.c" />
     <ClCompile Include="..\..\UniQuake\uniquake.c" />
   </ItemGroup>
diff --git a/engine/Windows/VisualStudio/uniquake.vcxproj.filters b/engine/Windows/VisualStudio/uniquake.vcxproj.filters
index 24de093..12f73e3 100644
--- a/engine/Windows/VisualStudio/uniquake.vcxproj.filters
+++ b/engine/Windows/VisualStudio/uniquake.vcxproj.filters
@@ -238,6 +238,9 @@
     <ClCompile Include="..\..\Quake\snd_codec.c">
       <Filter>obsolete</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\UniQuake\stub\stub_opengl.c">
+      <Filter>stub</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="..\..\Quake\anorm_dots.h">
@@ -470,5 +473,8 @@
     <Filter Include="fmod">
       <UniqueIdentifier>{d5c16a8d-ccc3-411a-831d-d2e8f4bf2219}</UniqueIdentifier>
     </Filter>
+    <Filter Include="stub">
+      <UniqueIdentifier>{049ed891-83c0-4948-a9b1-e4688933c0e5}</UniqueIdentifier>
+    </Filter>
   </ItemGroup>
 </Project>
\ No newline at end of file