[client] added renderer abstratction

This moves the bulk of the rendering code into seperate rendering
modules cleaning up much of intertwined SDL & OpenGL mess.

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "vendor/kvm-guest-drivers-windows"]
 	path = vendor/kvm-guest-drivers-windows
 	url = https://github.com/virtio-win/kvm-guest-drivers-windows.git
+[submodule "client/cimgui"]
+	path = client/cimgui
+	url = https://github.com/Extrawurst/cimgui.git

client/.gitignore

@@ -1,2 +1,3 @@
 bin/
+.build/
 *.swp

client/Makefile

@@ -2,6 +2,10 @@ BINARY  = looking-glass-client
 CFLAGS  = -g -Og -std=gnu99 -march=native -Wall -Werror -I./ -I../common -DDEBUG
 LDFLAGS = -lrt
 
+CFLAGS  += -ffast-math
+CFLAGS  += -fdata-sections -ffunction-sections
+LDFLAGS += -Wl,--gc-sections
+
 LIBS    = sdl2 SDL2_ttf gl glu libssl openssl spice-protocol
 CFLAGS  += $(shell pkg-config --cflags $(LIBS))
 LDFLAGS += $(shell pkg-config --libs   $(LIBS))
@@ -10,19 +14,21 @@ BIN     ?= bin
 
 OBJS	= main.o \
 	  spice/spice.o \
-	  ivshmem/ivshmem.o
+	  ivshmem/ivshmem.o \
+	  renderers/basic.o \
+	  renderers/opengl.o
 
 BUILD_OBJS = $(foreach obj,$(OBJS),$(BUILD)/$(obj))
 
-all: $(BINARY)
+all: $(BIN)/$(BINARY)
 
 $(BUILD)/%.o: %.c
 	@mkdir -p $(dir $@)
-	gcc -c $(CFLAGS) -o $@ $< $(LDFLAGS)
+	gcc -c $(CFLAGS) -o $@ $<
 
-$(BINARY): $(BUILD_OBJS)
+$(BIN)/$(BINARY): $(BUILD_OBJS)
 	@mkdir -p $(dir $(BIN)/$@)
-	gcc $(CFLAGS) -o $(BIN)/$(BINARY) $(BUILD_OBJS) $(LDFLAGS)
+	gcc -o $(BIN)/$(BINARY) $(BUILD_OBJS) $(LDFLAGS)
 
 clean:
 	rm -rf $(BUILD) $(BIN)

client/lg-renderer.h

@@ -0,0 +1,72 @@
+/*
+Looking Glass - KVM FrameRelay (KVMFR) Client
+Copyright (C) 2017 Geoffrey McRae <geoff@hostfission.com>
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; either version 2 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#pragma once
+#include <stdint.h>
+#include <stdbool.h>
+
+#include <SDL2/SDL.h>
+
+#define IS_LG_RENDERER_VALID(x) \
+  ((x)->get_name      && \
+   (x)->initialize    && \
+   (x)->deinitialize  && \
+   (x)->is_compatible && \
+   (x)->render)
+
+typedef struct LG_RendererParams
+{
+  SDL_Window   * window;
+  SDL_Renderer * renderer;
+}
+LG_RendererParams;
+
+typedef struct LG_RendererFormat
+{
+  unsigned int width;   // image width
+  unsigned int height;  // image height
+  unsigned int stride;  // scanline width
+  unsigned int pitch;   // scanline bytes
+  unsigned int bpp;     // bits per pixel
+}
+LG_RendererFormat;
+
+typedef struct LG_RendererRect
+{
+  int          x;
+  int          y;
+  unsigned int w;
+  unsigned int h;
+}
+LG_RendererRect;
+
+typedef const char * (* LG_RendererGetName     )();
+typedef bool         (* LG_RendererInitialize  )(void ** opaque, const LG_RendererParams params, const LG_RendererFormat format);
+typedef void         (* LG_RendererDeInitialize)(void * opaque);
+typedef bool         (* LG_RendererIsCompatible)(void * opaque, const LG_RendererFormat format);
+typedef bool         (* LG_RendererRender      )(void * opaque, const LG_RendererRect destRect, const uint8_t * data, bool resample);
+
+typedef struct LG_Renderer
+{
+  LG_RendererGetName      get_name;
+  LG_RendererInitialize   initialize;
+  LG_RendererDeInitialize deinitialize;
+  LG_RendererIsCompatible is_compatible;
+  LG_RendererRender       render;
+}
+LG_Renderer;

client/lg-renderers.h

@@ -0,0 +1,30 @@
+/*
+Looking Glass - KVM FrameRelay (KVMFR) Client
+Copyright (C) 2017 Geoffrey McRae <geoff@hostfission.com>
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; either version 2 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#pragma once
+#include "lg-renderer.h"
+
+extern const LG_Renderer LGR_OpenGL;
+extern const LG_Renderer LGR_Basic;
+
+const LG_Renderer * LG_Renderers[] =
+{
+  &LGR_OpenGL,
+  &LGR_Basic,
+  NULL // end of array sentinal
+};

client/main.c

@@ -40,6 +40,8 @@ Place, Suite 330, Boston, MA 02111-1307 USA
 #include "spice/spice.h"
 #include "kb.h"
 
+#include "lg-renderers.h"
+
 #define VBO_BUFFERS 2
 
 struct AppState
@@ -50,7 +52,8 @@ struct AppState
   bool      started;
 
   TTF_Font       *font;
-  SDL_Rect  srcRect, dstRect;
+  SDL_Rect        srcRect;
+  LG_RendererRect dstRect;
   float           scaleX, scaleY;
 
   SDL_Window         * window;
@@ -184,30 +187,14 @@ inline bool waitGuest()
 
 int renderThread(void * unused)
 {
+  bool                error = false;
   struct KVMFRHeader  header;
-  struct KVMFRHeader newHeader;
+  const LG_Renderer * lgr = NULL;
-  SDL_Texture        *texture      = NULL;
+  void              * lgrData;
-  GLuint              vboID[VBO_BUFFERS];
+  unsigned int        lastTicks = SDL_GetTicks();
-  GLuint              intFormat    = 0;
+  unsigned int        frameCount = 0, lastFrameCount = 0;
-  GLuint              vboFormat    = 0;
+  SDL_Texture       * textTexture = NULL;
-  GLuint              vboTex[VBO_BUFFERS];
+  SDL_Rect            textRect;
-  unsigned int        texIndex     = 0;
-  unsigned int        texSize      = 0;
-  uint8_t            *pixels       = (uint8_t*)state.shm;
-  uint8_t            *texPixels[VBO_BUFFERS];
-
-  unsigned int        ticks        = SDL_GetTicks();
-  unsigned int        frameCount   = 0;
-  SDL_Texture        *textTexture  = NULL;
-  SDL_Rect            textRect     = {0, 0, 0, 0};
-
-  memset(&header   , 0, sizeof(struct KVMFRHeader));
-  memset(&vboID    , 0, sizeof(vboID));
-  memset(&vboTex   , 0, sizeof(vboTex));
-  memset(&texPixels, 0, sizeof(texPixels));
-
-  // initial guest kick to get things started
-  ivshmem_kick_irq(state.shm->guestID, 0);
 
   while(state.running)
   {
@@ -215,145 +202,112 @@ int renderThread(void * unused)
     if (!waitGuest())
       break;
 
-    memcpy(&newHeader, state.shm, sizeof(struct KVMFRHeader));
+    // we must take a copy of the header, both to let the guest advance and to
+    // prevent the contained arguments being abused to overflow buffers
+    memcpy(&header, state.shm, sizeof(struct KVMFRHeader));
+    ivshmem_kick_irq(header.guestID, 0);
 
-    // ensure the header magic is valid, this will help prevent crash out when the memory hasn't yet been initialized
+    // check the header's magic and version are valid
     if (
-      memcmp(newHeader.magic, KVMFR_HEADER_MAGIC, sizeof(KVMFR_HEADER_MAGIC)) != 0 ||
+      memcmp(header.magic, KVMFR_HEADER_MAGIC, sizeof(KVMFR_HEADER_MAGIC)) != 0 ||
-      newHeader.version != KVMFR_HEADER_VERSION
+      header.version != KVMFR_HEADER_VERSION
     )
     {
       usleep(1000);
       continue;
     }
 
-    // if the header is invalid or it has changed
+    // setup the renderer format with the frame format details
-    if (!areFormatsSame(header, newHeader))
+    LG_RendererFormat lgrFormat;
-    {
+    lgrFormat.width  = header.width;
-      if (state.hasBufferStorage)
+    lgrFormat.height = header.height;
-      {
+    lgrFormat.stride = header.stride;
-        if (vboID[0])
-        {
-          if (vboTex[0])
-          {
-            glDeleteTextures(VBO_BUFFERS, vboTex);
-            memset(vboTex, 0, sizeof(vboTex));
-          }
 
-          glUnmapBuffer(GL_TEXTURE_BUFFER);
+    switch(header.frameType)
-          glDeleteBuffers(VBO_BUFFERS, vboID);
-          memset(vboID, 0, sizeof(vboID));
-        }
-      }
-      else
-      {
-        if (texture)
-        {
-          SDL_DestroyTexture(texture);
-          texture = NULL;
-        }
-      }
-
-      Uint32  sdlFormat;
-      unsigned int bpp;
-      switch(newHeader.frameType)
     {
       case FRAME_TYPE_ARGB:
-          sdlFormat = SDL_PIXELFORMAT_ARGB8888;
+        lgrFormat.pitch = header.stride * 4;
-          bpp       = 4;
+        lgrFormat.bpp   = 32;
-          intFormat = GL_RGBA8;
-          vboFormat = GL_BGRA;
         break;
 
       case FRAME_TYPE_RGB:
-          sdlFormat = SDL_PIXELFORMAT_RGB24;
+        lgrFormat.pitch = header.stride * 3;
-          bpp       = 3;
+        lgrFormat.bpp   = 24;
-          intFormat = GL_RGB8;
-          vboFormat = GL_BGR;
         break;
 
       default:
-          header.frameType = FRAME_TYPE_INVALID;
+        DEBUG_ERROR("Unsupported frameType");
-          continue;
+        error = true;
+        break;
     }
 
-      // update the window size and create the render texture
+    if (error)
-      if (params.autoResize)
+      break;
-      {
-        SDL_SetWindowSize(state.window, newHeader.width, newHeader.height);
-        if (params.center)
-          SDL_SetWindowPosition(state.window, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED);
-      }
 
-      if (state.hasBufferStorage)
+    // check the header's dataPos is sane
-      {
+    const size_t dataSize = lgrFormat.height * lgrFormat.pitch;
-        // calculate the texture size in bytes
+    if (header.dataPos + dataSize > state.shmSize)
-        texSize = newHeader.height * newHeader.stride * bpp;
-
-        // ensure the size makes sense
-        if (newHeader.dataPos + texSize > state.shmSize)
     {
       DEBUG_ERROR("The guest sent an invalid dataPos");
       break;
     }
 
-        // setup two buffers so we don't have to use fences
+    // check if we have a compatible renderer
-        glGenBuffers(VBO_BUFFERS, vboID);
+    if (!lgr || !lgr->is_compatible(lgrData, lgrFormat))
-        for (int i = 0; i < VBO_BUFFERS; ++i)
     {
-          glBindBuffer(GL_PIXEL_UNPACK_BUFFER, vboID[i]);
+      LG_RendererParams lgrParams;
-          glBufferStorage(GL_PIXEL_UNPACK_BUFFER, texSize, 0, GL_MAP_WRITE_BIT | GL_MAP_PERSISTENT_BIT);
+      lgrParams.window   = state.window;
-          texPixels[i] = glMapBufferRange(GL_PIXEL_UNPACK_BUFFER, 0, texSize,
+      lgrParams.renderer = state.renderer;
-              GL_MAP_WRITE_BIT | GL_MAP_PERSISTENT_BIT | GL_MAP_FLUSH_EXPLICIT_BIT);
-          if (!texPixels[i])
-          {
-            DEBUG_ERROR("Failed to map buffer range, turning off buffer storage");
-            state.hasBufferStorage = false;
-            break;
-          }
-          glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
-        }
 
-        if (!state.hasBufferStorage)
+      DEBUG_INFO("Data Format: w=%u, h=%u, s=%u, p=%u, bpp=%u",
-        {
+          lgrFormat.width, lgrFormat.height, lgrFormat.stride, lgrFormat.pitch, lgrFormat.bpp);
-          texIndex = 0;
-          glDeleteBuffers(VBO_BUFFERS, vboID);
-          memset(vboID, 0, sizeof(vboID));
-          continue;
-        }
 
-        // create the textures
+      // first try to reinitialize any existing renderer
-        glGenTextures(VBO_BUFFERS, vboTex);
+      if (lgr)
-        for (int i = 0; i < VBO_BUFFERS; ++i)
       {
-          glBindTexture(GL_TEXTURE_2D, vboTex[i]);
+        lgr->deinitialize(lgrData);
-          glTexImage2D(
+        if (lgr->initialize(&lgrData, lgrParams, lgrFormat))
-            GL_TEXTURE_2D,
+        {
-            0,
+          DEBUG_INFO("Reinitialized %s", lgr->get_name());
-            intFormat,
-            newHeader.width, newHeader.height,
-            0,
-            vboFormat,
-            GL_UNSIGNED_BYTE,
-            (void*)0
-          );
-          glBindTexture(GL_TEXTURE_2D, 0);
-        }
         }
         else
         {
-        texture = SDL_CreateTexture(state.renderer, sdlFormat, SDL_TEXTUREACCESS_STREAMING, newHeader.width, newHeader.height);
+          DEBUG_ERROR("Failed to reinitialize %s, trying other renderers", lgr->get_name());
-        if (!texture)
+          lgr->deinitialize(lgrData);
+          lgr = NULL;
+        }
+      }
+
+      if (!lgr)
       {
-          DEBUG_ERROR("Failed to create a texture");
+        // probe for a a suitable renderer
+        for(const LG_Renderer **r = &LG_Renderers[0]; *r; ++r)
+        {
+          if (!IS_LG_RENDERER_VALID(*r))
+          {
+            DEBUG_ERROR("FIXME: Renderer %d is invalid, skpping", (int)(r - &LG_Renderers[0]));
+            continue;
+          }
+
+          lgrData = NULL;
+          if (!(*r)->initialize(&lgrData, lgrParams, lgrFormat))
+          {
+            (*r)->deinitialize(lgrData);
+            continue;
+          }
+
+          lgr = *r;
+          DEBUG_INFO("Initialized %s", (*r)->get_name());
           break;
         }
+
+        if (!lgr)
+        {
+          DEBUG_INFO("Unable to find a suitable renderer");
+          return -1;
+        }
       }
 
-      ticks = SDL_GetTicks();
-      frameCount = 0;
-
-      memcpy(&header, &newHeader, sizeof(header));
       state.srcRect.x = 0;
       state.srcRect.y = 0;
       state.srcRect.w = header.width;
@@ -361,95 +315,27 @@ int renderThread(void * unused)
       updatePositionInfo();
     }
 
-    //beyond this point DO NOT use state.shm for security
+    if (!lgr->render(
-
+      lgrData,
-    // final sanity checks on the data presented by the guest
+      state.dstRect,
-    // this is critical as the guest could overflow this buffer to
+      (uint8_t *)state.shm + header.dataPos,
-    // try to take control of the host
+      params.useMipmap
-    if (newHeader.dataPos + texSize > state.shmSize)
+    ))
     {
-      DEBUG_ERROR("The guest sent an invalid dataPos");
+      DEBUG_ERROR("Failed to render the frame");
       break;
     }
 
-    SDL_RenderClear(state.renderer);
+    ++frameCount;
-    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
+    if (!params.showFPS)
-
-    if (state.hasBufferStorage)
     {
-      // copy the buffer to the texture and let the guest advance
+      SDL_RenderPresent(state.renderer);
-      memcpySSE(texPixels[texIndex], pixels + newHeader.dataPos, texSize);
+      continue;
-      glBindBuffer(GL_PIXEL_UNPACK_BUFFER, vboID[texIndex]);
-      glFlushMappedBufferRange(GL_PIXEL_UNPACK_BUFFER, 0, texSize);
-
-      // bind the texture and update it
-      glBindTexture(GL_TEXTURE_2D         , vboTex[texIndex]);
-      glPixelStorei(GL_UNPACK_ALIGNMENT   , 1               );
-      glPixelStorei(GL_UNPACK_ROW_LENGTH  , header.width    );
-      glTexSubImage2D(
-          GL_TEXTURE_2D,
-          0,
-          0, 0,
-          header.width, header.height,
-          vboFormat,
-          GL_UNSIGNED_BYTE,
-          (void*)0
-      );
-      if (params.useMipmap)
-        glGenerateMipmap(GL_TEXTURE_2D);
-
-      // unbind the buffer
-      glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
-
-      // configure the texture
-      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
-      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
-      if (params.useMipmap)
-      {
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
-      }
-      else
-      {
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
     }
 
-      // draw the screen
+    // for now render the frame counter here, we really should
-      glEnable(GL_TEXTURE_2D);
+    // move this into the renderers though.
-      glBegin(GL_TRIANGLE_STRIP);
+    if (frameCount % 10 == 0)
-        glTexCoord2f(0.0f, 0.0f); glVertex2i(state.dstRect.x                  , state.dstRect.y                  );
-        glTexCoord2f(1.0f, 0.0f); glVertex2i(state.dstRect.x + state.dstRect.w, state.dstRect.y                  );
-        glTexCoord2f(0.0f, 1.0f); glVertex2i(state.dstRect.x                  , state.dstRect.y + state.dstRect.h);
-        glTexCoord2f(1.0f, 1.0f); glVertex2i(state.dstRect.x + state.dstRect.w, state.dstRect.y + state.dstRect.h);
-      glEnd();
-      glDisable(GL_TEXTURE_2D);
-      glBindTexture(GL_TEXTURE_2D, 0);
-
-      // update our texture index
-      if (++texIndex == VBO_BUFFERS)
-        texIndex = 0;
-    }
-    else
-    {
-      int pitch;
-      if (SDL_LockTexture(texture, NULL, (void**)&texPixels[0], &pitch) != 0)
-      {
-        DEBUG_ERROR("Failed to lock the texture for update");
-        break;
-      }
-      texSize = header.height * pitch;
-
-      // copy the buffer to the texture and let the guest advance
-      memcpySSE(texPixels[texIndex], pixels + newHeader.dataPos, texSize);
-
-      SDL_UnlockTexture(texture);
-      SDL_RenderCopy(state.renderer, texture, NULL, &state.dstRect);
-    }
-
-    if (params.showFPS)
-    {
-      if (++frameCount == 10)
     {
       SDL_Surface *textSurface = NULL;
       if (textTexture)
@@ -457,8 +343,9 @@ int renderThread(void * unused)
         SDL_DestroyTexture(textTexture);
         textTexture = NULL;
       }
-        const unsigned int time = SDL_GetTicks();
+
-        const float avgFPS = (float)frameCount / ((time - ticks) / 1000.0f);
+      const unsigned int ticks = SDL_GetTicks();
+      const float avgFPS = (float)(frameCount - lastFrameCount) / ((ticks - lastTicks) / 1000.0f);
       char strFPS[12];
       snprintf(strFPS, sizeof(strFPS), "FPS: %6.2f", avgFPS);
       SDL_Color color = {0xff, 0xff, 0xff};
@@ -477,8 +364,8 @@ int renderThread(void * unused)
       SDL_SetTextureBlendMode(textTexture, SDL_BLENDMODE_BLEND);
       SDL_FreeSurface(textSurface);
 
-        frameCount = 0;
+      lastTicks      = ticks;
-        ticks = time;
+      lastFrameCount = frameCount;
     }
 
     if (textTexture)
@@ -507,24 +394,12 @@ int renderThread(void * unused)
       glDisable(GL_BLEND);
       SDL_GL_UnbindTexture(textTexture);
     }
-    }
 
     SDL_RenderPresent(state.renderer);
-    ivshmem_kick_irq(newHeader.guestID, 0);
-
-    state.started = true;
   }
 
-  state.running = false;
+  if (lgr)
-  if (state.hasBufferStorage)
+    lgr->deinitialize(lgrData);
-  {
-    glDeleteTextures(VBO_BUFFERS, vboTex);
-    glUnmapBuffer   (GL_TEXTURE_BUFFER  );
-    glDeleteBuffers (VBO_BUFFERS, vboID );
-  }
-  else
-    if (texture)
-      SDL_DestroyTexture(texture);
 
   return 0;
 }
@@ -833,14 +708,10 @@ int run()
     (params.vsync ? SDL_RENDERER_PRESENTVSYNC : 0)
   );
 
-  if (params.useBufferStorage)
+  if (!state.renderer)
   {
-    const GLubyte * extensions = glGetString(GL_EXTENSIONS);
+    DEBUG_ERROR("failed to create renderer");
-    if (gluCheckExtension((const GLubyte *)"GL_ARB_buffer_storage", extensions))
+    return -1;
-    {
-      DEBUG_INFO("Using GL_ARB_buffer_storage");
-      state.hasBufferStorage = true;
-    }
   }
 
   if (params.vsync)
@@ -852,10 +723,14 @@ int run()
   else
     SDL_GL_SetSwapInterval(0);
 
-  if (!state.renderer)
+  if (params.useBufferStorage)
   {
-    DEBUG_ERROR("failed to create window");
+    const GLubyte * extensions = glGetString(GL_EXTENSIONS);
-    return -1;
+    if (gluCheckExtension((const GLubyte *)"GL_ARB_buffer_storage", extensions))
+    {
+      DEBUG_INFO("Using GL_ARB_buffer_storage");
+      state.hasBufferStorage = true;
+    }
   }
 
   int         shm_fd    = 0;

client/renderers/basic.c

@@ -0,0 +1,146 @@
+#include "lg-renderer.h"
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <SDL2/SDL.h>
+
+#include "debug.h"
+#include "memcpySSE.h"
+
+struct LGR_Basic
+{
+  bool               initialized;
+  LG_RendererFormat  format;
+  size_t             texSize;
+  size_t             dataWidth;
+  SDL_Renderer     * renderer;
+  SDL_Texture      * texture;
+};
+
+const char * lgr_basic_get_name()
+{
+  return "Basic";
+}
+
+bool lgr_basic_initialize(void ** opaque, const LG_RendererParams params, const LG_RendererFormat format)
+{
+  // create our local storage
+  *opaque = malloc(sizeof(struct LGR_Basic));
+  if (!*opaque)
+  {
+    DEBUG_INFO("Failed to allocate %lu bytes", sizeof(struct LGR_Basic));
+    return false;
+  }
+  memset(*opaque, 0, sizeof(struct LGR_Basic));
+  struct LGR_Basic * this = (struct LGR_Basic *)*opaque;
+
+  Uint32 sdlFormat;
+  switch(format.bpp)
+  {
+    case 24:
+      sdlFormat = SDL_PIXELFORMAT_RGB24;
+      break;
+
+    case 32:
+      sdlFormat = SDL_PIXELFORMAT_ARGB8888;
+      break;
+
+    default:
+      DEBUG_ERROR("Unsupported bpp");
+      return false;
+  }
+
+  // calculate the texture size in bytes
+  this->texSize = format.height * format.pitch;
+
+  // create the target texture
+  this->texture = SDL_CreateTexture(
+    params.renderer,
+    sdlFormat,
+    SDL_TEXTUREACCESS_STREAMING,
+    format.width,
+    format.height
+  );
+
+  if (!this->texture)
+  {
+    DEBUG_ERROR("SDL_CreateTexture failed");
+    return false;
+  }
+
+
+  memcpy(&this->format, &format, sizeof(LG_RendererFormat));
+  this->renderer    = params.renderer;
+  this->dataWidth   = this->format.width * (this->format.bpp / 8);
+  this->initialized = true;
+  return true;
+}
+
+void lgr_basic_deinitialize(void * opaque)
+{
+  struct LGR_Basic * this = (struct LGR_Basic *)opaque;
+  if (!this)
+    return;
+
+  if (this->texture)
+    SDL_DestroyTexture(this->texture);
+
+  free(this);
+}
+
+bool lgr_basic_is_compatible(void * opaque, const LG_RendererFormat format)
+{
+  const struct LGR_Basic * this = (struct LGR_Basic *)opaque;
+  if (!this || !this->initialized)
+    return false;
+
+  return (memcmp(&this->format, &format, sizeof(LG_RendererFormat)) == 0);
+}
+
+bool lgr_basic_render(void * opaque, const LG_RendererRect destRect, const uint8_t * data, bool resample)
+{
+  struct LGR_Basic * this = (struct LGR_Basic *)opaque;
+  if (!this || !this->initialized)
+    return false;
+
+  int       pitch;
+  uint8_t * dest;
+
+  if (SDL_LockTexture(this->texture, NULL, (void**)&dest, &pitch) != 0)
+  {
+    DEBUG_ERROR("Failed to lock the texture for update");
+    return false;
+  }
+
+  if (pitch == this->format.pitch)
+    memcpySSE(dest, data, this->texSize);
+  else
+  {
+    for(unsigned int y = 0; y < this->format.height; ++y)
+    {
+      memcpySSE(dest, data, this->dataWidth);
+      dest += pitch;
+      data += this->format.pitch;
+    }
+  }
+
+  SDL_Rect rect;
+  rect.x = destRect.x;
+  rect.y = destRect.y;
+  rect.w = destRect.w;
+  rect.h = destRect.h;
+
+  SDL_UnlockTexture(this->texture);
+  SDL_RenderCopy(this->renderer, this->texture, NULL, &rect);
+
+  return true;
+}
+
+const LG_Renderer LGR_Basic =
+{
+  .get_name      = lgr_basic_get_name,
+  .initialize    = lgr_basic_initialize,
+  .deinitialize  = lgr_basic_deinitialize,
+  .is_compatible = lgr_basic_is_compatible,
+  .render        = lgr_basic_render
+};

client/renderers/opengl.c

@@ -0,0 +1,255 @@
+#include "lg-renderer.h"
+#include <stdint.h>
+#include <stdbool.h>
+
+#define GL_GLEXT_PROTOTYPES
+#include <GL/gl.h>
+#include <GL/glu.h>
+
+#include "debug.h"
+#include "memcpySSE.h"
+
+#define VBO_BUFFERS 2
+
+struct LGR_OpenGL
+{
+  bool              initialized;
+  LG_RendererFormat format;
+  GLuint            intFormat;
+  GLuint            vboFormat;
+  size_t            texSize;
+
+  bool              hasBuffers;
+  GLuint            vboID[VBO_BUFFERS];
+  uint8_t         * texPixels[VBO_BUFFERS];
+  int               texIndex;
+
+  bool              hasTextures;
+  GLuint            vboTex[VBO_BUFFERS];
+};
+
+bool lgr_opengl_check_error(const char * name)
+{
+  GLenum error = glGetError();
+  if (error == GL_NO_ERROR)
+    return false;
+
+  const GLubyte * errStr = gluErrorString(error);
+  DEBUG_ERROR("%s = %d (%s)", name, error, errStr);
+  return true;
+}
+
+const char * lgr_opengl_get_name()
+{
+  return "OpenGL";
+}
+
+bool lgr_opengl_initialize(void ** opaque, const LG_RendererParams params, const LG_RendererFormat format)
+{
+  // check if the GPU supports GL_ARB_buffer_storage first
+  // there is no advantage to this renderer if it is not present.
+  const GLubyte * extensions = glGetString(GL_EXTENSIONS);
+  if (!gluCheckExtension((const GLubyte *)"GL_ARB_buffer_storage", extensions))
+  {
+    DEBUG_INFO("The GPU doesn't support GL_ARB_buffer_storage");
+    return false;
+  }
+
+  // create our local storage
+  *opaque = malloc(sizeof(struct LGR_OpenGL));
+  if (!*opaque)
+  {
+    DEBUG_INFO("Failed to allocate %lu bytes", sizeof(struct LGR_OpenGL));
+    return false;
+  }
+  memset(*opaque, 0, sizeof(struct LGR_OpenGL));
+  struct LGR_OpenGL * this = (struct LGR_OpenGL *)*opaque;
+
+  // assume 24 and 32 bit formats are RGB and RGBA
+  switch(format.bpp)
+  {
+    case 24:
+      this->intFormat = GL_RGB8;
+      this->vboFormat = GL_BGR;
+      break;
+
+    case 32:
+      this->intFormat = GL_RGBA8;
+      this->vboFormat = GL_BGRA;
+      break;
+
+    default:
+      DEBUG_INFO("%d bpp not supported", format.bpp);
+      return false;
+  }
+
+  // calculate the texture size in bytes
+  this->texSize = format.height * format.pitch;
+
+  // generate the pixel unpack buffers
+  glGenBuffers(VBO_BUFFERS, this->vboID);
+  if (lgr_opengl_check_error("glGenBuffers"))
+    return false;
+  this->hasBuffers = true;
+
+  // persistant bind the buffers
+  for (int i = 0; i < VBO_BUFFERS; ++i)
+  {
+    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, this->vboID[i]);
+    if (lgr_opengl_check_error("glBindBuffer"))
+      return false;
+
+    glBufferStorage(GL_PIXEL_UNPACK_BUFFER, this->texSize, 0, GL_MAP_WRITE_BIT | GL_MAP_PERSISTENT_BIT);
+    if (lgr_opengl_check_error("glBufferStorage"))
+      return false;
+
+    this->texPixels[i] = glMapBufferRange(GL_PIXEL_UNPACK_BUFFER, 0, this->texSize,
+        GL_MAP_WRITE_BIT | GL_MAP_PERSISTENT_BIT | GL_MAP_FLUSH_EXPLICIT_BIT);
+    if (lgr_opengl_check_error("glMapBufferRange"))
+      return false;
+
+    if (!this->texPixels[i])
+    {
+      DEBUG_ERROR("Failed to map the buffer range");
+      return false;
+    }
+
+    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
+  }
+
+  // create the textures
+  glGenTextures(VBO_BUFFERS, this->vboTex);
+  if (lgr_opengl_check_error("glGenTextures"))
+    return false;
+  this->hasTextures = true;
+
+  // bind the textures to the unpack buffers
+  for (int i = 0; i < VBO_BUFFERS; ++i)
+  {
+    glBindTexture(GL_TEXTURE_2D, this->vboTex[i]);
+    if (lgr_opengl_check_error("glBindTexture"))
+      return false;
+
+    glTexImage2D(
+      GL_TEXTURE_2D,
+      0,
+      this->intFormat,
+      format.width, format.height,
+      0,
+      this->vboFormat,
+      GL_UNSIGNED_BYTE,
+      (void*)0
+    );
+
+    if (lgr_opengl_check_error("glTexImage2D"))
+      return false;
+  }
+
+  glEnable(GL_TEXTURE_2D);
+
+  // copy the format into the local storage
+  memcpy(&this->format, &format, sizeof(LG_RendererFormat));
+  this->initialized = true;
+  return true;
+}
+
+void lgr_opengl_deinitialize(void * opaque)
+{
+  struct LGR_OpenGL * this = (struct LGR_OpenGL *)opaque;
+  if (!this)
+    return;
+
+  if (this->hasTextures)
+    glDeleteTextures(VBO_BUFFERS, this->vboTex);
+
+  if (this->hasBuffers)
+    glDeleteBuffers(VBO_BUFFERS, this->vboID);
+
+  free(this);
+}
+
+bool lgr_opengl_is_compatible(void * opaque, const LG_RendererFormat format)
+{
+  const struct LGR_OpenGL * this = (struct LGR_OpenGL *)opaque;
+  if (!this || !this->initialized)
+    return false;
+
+  return (memcmp(&this->format, &format, sizeof(LG_RendererFormat)) == 0);
+}
+
+bool lgr_opengl_render(void * opaque, const LG_RendererRect destRect, const uint8_t * data, bool resample)
+{
+  struct LGR_OpenGL * this = (struct LGR_OpenGL *)opaque;
+  if (!this || !this->initialized)
+    return false;
+
+  glClear(GL_COLOR_BUFFER_BIT);
+
+  // copy the buffer to the texture
+  memcpySSE(this->texPixels[this->texIndex], data, this->texSize);
+  glBindBuffer(GL_PIXEL_UNPACK_BUFFER, this->vboID[this->texIndex]);
+  glFlushMappedBufferRange(GL_PIXEL_UNPACK_BUFFER, 0, this->texSize);
+
+  // bind the texture and update it
+  glBindTexture(GL_TEXTURE_2D         , this->vboTex[this->texIndex]);
+  glPixelStorei(GL_UNPACK_ALIGNMENT   , 4                           );
+  glPixelStorei(GL_UNPACK_ROW_LENGTH  , this->format.width          );
+  glTexSubImage2D(
+    GL_TEXTURE_2D,
+    0,
+    0, 0,
+    this->format.width,
+    this->format.height,
+    this->vboFormat,
+    GL_UNSIGNED_BYTE,
+    (void*)0
+  );
+
+  const bool mipmap = resample && (
+    (this->format.width  != destRect.w) ||
+    (this->format.height != destRect.h));
+
+  // unbind the buffer
+  glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
+
+  // configure the texture
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+  if (mipmap)
+  {
+    glGenerateMipmap(GL_TEXTURE_2D);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
+  }
+  else
+  {
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+  }
+
+  // draw the screen
+  glEnable(GL_TEXTURE_2D);
+  glBegin(GL_TRIANGLE_STRIP);
+    glTexCoord2f(0.0f, 0.0f); glVertex2i(destRect.x             , destRect.y             );
+    glTexCoord2f(1.0f, 0.0f); glVertex2i(destRect.x + destRect.w, destRect.y             );
+    glTexCoord2f(0.0f, 1.0f); glVertex2i(destRect.x             , destRect.y + destRect.h);
+    glTexCoord2f(1.0f, 1.0f); glVertex2i(destRect.x + destRect.w, destRect.y + destRect.h);
+  glEnd();
+  glDisable(GL_TEXTURE_2D);
+
+  glBindTexture(GL_TEXTURE_2D, 0);
+
+  if (++this->texIndex == VBO_BUFFERS)
+    this->texIndex = 0;
+
+  return true;
+}
+
+const LG_Renderer LGR_OpenGL =
+{
+  .get_name      = lgr_opengl_get_name,
+  .initialize    = lgr_opengl_initialize,
+  .deinitialize  = lgr_opengl_deinitialize,
+  .is_compatible = lgr_opengl_is_compatible,
+  .render        = lgr_opengl_render
+};