prevent race condition around framebuffers

4 files changed, 106 insertions, 68 deletions

diff --git a/src/GPU.h b/src/GPU.h
index 3a254df..2fc15f4 100644
--- a/src/GPU.h
+++ b/src/GPU.h
@@ -563,7 +563,7 @@ void SetRenderSettings(RenderSettings& settings);
 
 void Stop();
 void RenderFrame();
-void BindOutputTexture();
+void BindOutputTexture(int buf);
 
 }
 #endif
diff --git a/src/GPU_OpenGL.cpp b/src/GPU_OpenGL.cpp
index 59ced93..e7ab1f7 100644
--- a/src/GPU_OpenGL.cpp
+++ b/src/GPU_OpenGL.cpp
@@ -49,8 +49,8 @@ struct CompVertex
 CompVertex CompVertices[2 * 3*2];
 
 GLuint CompScreenInputTex;
-GLuint CompScreenOutputTex;
-GLuint CompScreenOutputFB;
+GLuint CompScreenOutputTex[2];
+GLuint CompScreenOutputFB[2];
 
 
 bool Init()
@@ -118,7 +118,7 @@ bool Init()
     glEnableVertexAttribArray(1); // texcoord
     glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(CompVertex), (void*)(offsetof(CompVertex, Texcoord)));
 
-    glGenFramebuffers(1, &CompScreenOutputFB);
+    glGenFramebuffers(2, CompScreenOutputFB);
 
     glGenTextures(1, &CompScreenInputTex);
     glActiveTexture(GL_TEXTURE0);
@@ -129,12 +129,15 @@ bool Init()
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8UI, 256*3 + 1, 192*2, 0, GL_RGBA_INTEGER, GL_UNSIGNED_BYTE, NULL);
 
-    glGenTextures(1, &CompScreenOutputTex);
-    glBindTexture(GL_TEXTURE_2D, CompScreenOutputTex);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glGenTextures(2, CompScreenOutputTex);
+    for (int i = 0; i < 2; i++)
+    {
+        glBindTexture(GL_TEXTURE_2D, CompScreenOutputTex[i]);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    }
 
     glBindFramebuffer(GL_FRAMEBUFFER, 0);
 
@@ -143,9 +146,9 @@ bool Init()
 
 void DeInit()
 {
-    glDeleteFramebuffers(1, &CompScreenOutputFB);
+    glDeleteFramebuffers(2, CompScreenOutputFB);
     glDeleteTextures(1, &CompScreenInputTex);
-    glDeleteTextures(1, &CompScreenOutputTex);
+    glDeleteTextures(2, CompScreenOutputTex);
 
     glDeleteVertexArrays(1, &CompVertexArrayID);
     glDeleteBuffers(1, &CompVertexBufferID);
@@ -167,30 +170,41 @@ void SetRenderSettings(RenderSettings& settings)
     ScreenW = 256 * scale;
     ScreenH = (384+2) * scale;
 
-    glBindTexture(GL_TEXTURE_2D, CompScreenOutputTex);
-    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, ScreenW, ScreenH, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
-    // fill the padding
-    u8 zeroPixels[ScreenW*2*scale*4];
-    memset(zeroPixels, 0, sizeof(zeroPixels));
-    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 192*scale, ScreenW, 2*scale, GL_RGBA, GL_UNSIGNED_BYTE, zeroPixels);
-
-    GLenum fbassign[] = {GL_COLOR_ATTACHMENT0};
-    glBindFramebuffer(GL_FRAMEBUFFER, CompScreenOutputFB);
-    glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, CompScreenOutputTex, 0);
-    glDrawBuffers(1, fbassign);
+    for (int i = 0; i < 2; i++)
+    {
+        glBindTexture(GL_TEXTURE_2D, CompScreenOutputTex[i]);
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, ScreenW, ScreenH, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
+        // fill the padding
+        u8 zeroPixels[ScreenW*2*scale*4];
+        memset(zeroPixels, 0, sizeof(zeroPixels));
+        glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 192*scale, ScreenW, 2*scale, GL_RGBA, GL_UNSIGNED_BYTE, zeroPixels);
+
+        GLenum fbassign[] = {GL_COLOR_ATTACHMENT0};
+        glBindFramebuffer(GL_FRAMEBUFFER, CompScreenOutputFB[i]);
+        glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, CompScreenOutputTex[i], 0);
+        glDrawBuffers(1, fbassign);
+    }
 
     glBindFramebuffer(GL_FRAMEBUFFER, 0);
 }
 
 void Stop()
 {
-    RenderFrame();
+    for (int i = 0; i < 2; i++)
+    {
+        int frontbuf = GPU::FrontBuffer;
+        glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
+        glBindFramebuffer(GL_DRAW_FRAMEBUFFER, CompScreenOutputFB[frontbuf]);
+
+        glClear(GL_COLOR_BUFFER_BIT);
+    }
 }
 
 void RenderFrame()
 {
+    int frontbuf = GPU::FrontBuffer;
     glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
-    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, CompScreenOutputFB);
+    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, CompScreenOutputFB[frontbuf]);
 
     glDisable(GL_DEPTH_TEST);
     glDisable(GL_STENCIL_TEST);
@@ -208,7 +222,6 @@ void RenderFrame()
     // TODO: support setting this midframe, if ever needed
     glUniform1i(Comp3DXPosLoc[0], ((int)GPU3D::RenderXPos << 23) >> 23);
 
-    int frontbuf = GPU::FrontBuffer;
     glActiveTexture(GL_TEXTURE0);
     glBindTexture(GL_TEXTURE_2D, CompScreenInputTex);
 
@@ -228,9 +241,9 @@ void RenderFrame()
     glDrawArrays(GL_TRIANGLES, 0, 4*3);
 }
 
-void BindOutputTexture()
+void BindOutputTexture(int buf)
 {
-    glBindTexture(GL_TEXTURE_2D, CompScreenOutputTex);
+    glBindTexture(GL_TEXTURE_2D, CompScreenOutputTex[buf]);
 }
 
 }
diff --git a/src/frontend/qt_sdl/main.cpp b/src/frontend/qt_sdl/main.cpp
index 6766252..5aa4959 100644
--- a/src/frontend/qt_sdl/main.cpp
+++ b/src/frontend/qt_sdl/main.cpp
@@ -490,13 +490,18 @@ void EmuThread::run()
             // emulate
             u32 nlines = NDS::RunFrame();
 
+            FrontBufferLock.lock();
 #ifdef OGLRENDERER_ENABLED
-            // this is hacky but this is the easiest way to call
-            // this function without dealling with a ton of
-            // macro mess
             if (videoRenderer == 1)
-                epoxy_glFlush();
+            {
+                // this is hacky but this is the easiest way to call
+                // this function without dealling with a ton of
+                // macro mess
+                epoxy_glFinish();
+            }
 #endif
+            FrontBuffer = GPU::FrontBuffer;
+            FrontBufferLock.unlock();
 
 #ifdef MELONCAP
             MelonCap::Update();
@@ -824,11 +829,17 @@ void ScreenPanelNative::paintEvent(QPaintEvent* event)
     // fill background
     painter.fillRect(event->rect(), QColor::fromRgb(0, 0, 0));
 
-    int frontbuf = GPU::FrontBuffer;
-    if (!GPU::Framebuffer[frontbuf][0] || !GPU::Framebuffer[frontbuf][1]) return;
+    emuThread->FrontBufferLock.lock();
+    int frontbuf = emuThread->FrontBuffer;
+    if (!GPU::Framebuffer[frontbuf][0] || !GPU::Framebuffer[frontbuf][1])
+    {
+        emuThread->FrontBufferLock.unlock();
+        return;
+    }
 
     memcpy(screen[0].scanLine(0), GPU::Framebuffer[frontbuf][0], 256*192*4);
     memcpy(screen[1].scanLine(0), GPU::Framebuffer[frontbuf][1], 256*192*4);
+    emuThread->FrontBufferLock.unlock();
 
     painter.setRenderHint(QPainter::SmoothPixmapTransform, Config::ScreenFilter!=0);
 
@@ -988,53 +999,63 @@ void ScreenPanelGL::paintGL()
 
     glViewport(0, 0, w*factor, h*factor);
 
-    screenShader->bind();
+    if (emuThread)
+    {
+        screenShader->bind();
 
-    screenShader->setUniformValue("uScreenSize", (float)w*factor, (float)h*factor);
+        screenShader->setUniformValue("uScreenSize", (float)w*factor, (float)h*factor);
 
-    int frontbuf = GPU::FrontBuffer;
-    glActiveTexture(GL_TEXTURE0);
+        emuThread->FrontBufferLock.lock();
+        int frontbuf = emuThread->FrontBuffer;
+        glActiveTexture(GL_TEXTURE0);
 
-#ifdef OGLRENDERER_ENABLED
-    if (GPU::Renderer != 0)
-    {
-        // hardware-accelerated render
-        GPU::GLCompositor::BindOutputTexture();
-    }
-    else
-#endif
-    {
-        // regular render
-        glBindTexture(GL_TEXTURE_2D, screenTexture);
-
-        if (GPU::Framebuffer[frontbuf][0] && GPU::Framebuffer[frontbuf][1])
+    #ifdef OGLRENDERER_ENABLED
+        if (GPU::Renderer != 0)
         {
-            glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 256, 192, GL_RGBA,
-                            GL_UNSIGNED_BYTE, GPU::Framebuffer[frontbuf][0]);
-            glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 192+2, 256, 192, GL_RGBA,
-                            GL_UNSIGNED_BYTE, GPU::Framebuffer[frontbuf][1]);
+            // hardware-accelerated render
+            GPU::GLCompositor::BindOutputTexture(frontbuf);
         }
-    }
+        else
+    #endif
+        {
+            // regular render
+            glBindTexture(GL_TEXTURE_2D, screenTexture);
 
-    GLint filter = Config::ScreenFilter ? GL_LINEAR : GL_NEAREST;
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, filter);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, filter);
+            if (GPU::Framebuffer[frontbuf][0] && GPU::Framebuffer[frontbuf][1])
+            {
+                glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 256, 192, GL_RGBA,
+                                GL_UNSIGNED_BYTE, GPU::Framebuffer[frontbuf][0]);
+                glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 192+2, 256, 192, GL_RGBA,
+                                GL_UNSIGNED_BYTE, GPU::Framebuffer[frontbuf][1]);
+            }
+        }
 
-    glBindBuffer(GL_ARRAY_BUFFER, screenVertexBuffer);
-    glBindVertexArray(screenVertexArray);
+        GLint filter = Config::ScreenFilter ? GL_LINEAR : GL_NEAREST;
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, filter);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, filter);
 
-    GLint transloc = screenShader->uniformLocation("uTransform");
+        glBindBuffer(GL_ARRAY_BUFFER, screenVertexBuffer);
+        glBindVertexArray(screenVertexArray);
 
-    for (int i = 0; i < numScreens; i++)
-    {
-        glUniformMatrix2x3fv(transloc, 1, GL_TRUE, screenMatrix[i]);
-        glDrawArrays(GL_TRIANGLES, screenKind[i] == 0 ? 0 : 2*3, 2*3);
-    }
+        GLint transloc = screenShader->uniformLocation("uTransform");
 
-    screenShader->release();
+        for (int i = 0; i < numScreens; i++)
+        {
+            glUniformMatrix2x3fv(transloc, 1, GL_TRUE, screenMatrix[i]);
+            glDrawArrays(GL_TRIANGLES, screenKind[i] == 0 ? 0 : 2*3, 2*3);
+        }
+
+        screenShader->release();
+    }
 
     OSD::Update(this);
     OSD::DrawGL(this, w*factor, h*factor);
+
+    if (emuThread)
+    {
+        glFinish();
+        emuThread->FrontBufferLock.unlock();
+    }
 }
 
 void ScreenPanelGL::resizeEvent(QResizeEvent* event)
diff --git a/src/frontend/qt_sdl/main.h b/src/frontend/qt_sdl/main.h
index c226fbc..9bfcd0a 100644
--- a/src/frontend/qt_sdl/main.h
+++ b/src/frontend/qt_sdl/main.h
@@ -26,6 +26,7 @@
 #include <QImage>
 #include <QActionGroup>
 #include <QTimer>
+#include <QMutex>
 
 #include <QOffscreenSurface>
 #include <QOpenGLWidget>
@@ -59,6 +60,9 @@ public:
 
     bool emuIsRunning();
 
+    int FrontBuffer = 0;
+    QMutex FrontBufferLock;
+
 signals:
     void windowUpdate();
     void windowTitleChange(QString title);