Add native Libretro supersampling

Makefile

@@ -244,6 +244,7 @@ endif
 
 ifneq ($(filter $(platform),android rpi64 aarch64),$(platform))
     RENDERER_DEFINES += -DHAVE_CRT_COLOURS
+    RENDERER_DEFINES += -DHAVE_SUPERSAMPLING
 endif
 
 # GIT version

Src/Graphics/SuperAA.cpp

@@ -4,9 +4,10 @@
 
 SuperAA::SuperAA(int aaValue, CRTcolor CRTcolors) :
 	m_aa(aaValue),
-	m_crtcolors(CRTcolors),
-	m_vao(0),
-	m_width(0),
+	m_crtcolors(CRTcolors),
+	m_vao(0),
+	m_outputTarget(0),
+	m_width(0),
 	m_height(0)
 {
 	if ((m_aa > 1) || (m_crtcolors != CRTcolor::None)) {
@@ -203,25 +204,30 @@ void SuperAA::Init(int width, int height)
 	}
 }
 
-void SuperAA::Draw()
-{
-	if ((m_aa > 1) || (m_crtcolors != CRTcolor::None)) {
-		glDisable(GL_DEPTH_TEST);
-		glDisable(GL_STENCIL_TEST);
-		glDisable(GL_SCISSOR_TEST);
-		glDisable(GL_BLEND);
-
-		glBindTexture(GL_TEXTURE_2D, m_fbo.GetTextureID());
+void SuperAA::Draw()
+{
+	if ((m_aa > 1) || (m_crtcolors != CRTcolor::None)) {
+		glBindFramebuffer(GL_FRAMEBUFFER, m_outputTarget);
+		glDisable(GL_DEPTH_TEST);
+		glDisable(GL_STENCIL_TEST);
+		glDisable(GL_SCISSOR_TEST);
+		glDisable(GL_BLEND);
+		glBindTexture(GL_TEXTURE_2D, m_fbo.GetTextureID());
 		glBindVertexArray(m_vao);
 		glViewport(0, 0, m_width, m_height);
 		m_shader.EnableShader();
 		glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
 		m_shader.DisableShader();
 		glBindVertexArray(0);
-	}
-}
-
-GLuint SuperAA::GetTargetID()
+	}
+}
+
+void SuperAA::SetOutputTarget(GLuint fbo)
+{
+	m_outputTarget = fbo;
+}
+
+GLuint SuperAA::GetTargetID()
 {
 	return m_fbo.GetFBOID();	// will return 0 if no render target which will be our default frame buffer (back buffer)
 }

Src/Graphics/SuperAA.h

@@ -16,17 +16,19 @@ public:
 	SuperAA(int aaValue, CRTcolor CRTcolors);
 	~SuperAA();
 
-	void Init(int width, int height);		// width & height are real window dimensions
-	void Draw();							// this is a no-op if AA is 1 and CRTcolors 0, since we'll be drawing straight on the back buffer anyway
-
-	GLuint GetTargetID();
+	void Init(int width, int height);		// width & height are real window dimensions
+	void Draw();							// this is a no-op if AA is 1 and CRTcolors 0, since we'll be drawing straight on the back buffer anyway
+	void SetOutputTarget(GLuint fbo);		// optional resolved output FBO (0 = window backbuffer)
+
+	GLuint GetTargetID();
 
 private:
 	FBO m_fbo;
 	GLSLShader m_shader;
 	const int m_aa;
 	const CRTcolor m_crtcolors;
-	GLuint m_vao;
-	int m_width;
+	GLuint m_vao;
+	GLuint m_outputTarget;
+	int m_width;
 	int m_height;
 };

Src/OSD/libretro/CoreOptionsTypes.h

@@ -50,6 +50,7 @@ struct CoreOptions {
    Renderer3D renderer_3d;
    bool quad_rendering;
    int crt_colors;
+   int supersampling;
    int upscale_mode;
    WidescreenMode widescreen_mode;
    unsigned crosshairs;      // native Supermodel mask: 0=off, 1=P1, 2=P2, 3=both

Src/OSD/libretro/LibretroConfigProvider.h

@@ -338,6 +338,7 @@ namespace LibretroConfigProvider {
                    !use_legacy_3d && g_options.quad_rendering);
         config.Set("CRTcolors",
                    !use_legacy_3d ? g_options.crt_colors : 0);
+        config.Set("Supersampling", g_options.supersampling);
         config.Set("UpscaleMode", g_options.upscale_mode);
         config.Set("WideScreen",
                    g_options.widescreen_mode != WidescreenMode::Disabled);

Src/OSD/libretro/LibretroWrapper.cpp

@@ -380,43 +380,45 @@ bool LibretroWrapper::InitRenderers()
     superAA = new SuperAA(aaValue, CRTcolors);
     superAA->Init(totalXRes, totalYRes);
 
-    GLuint renderTarget = superAA->GetTargetID();
-
-    // SuperAA skips FBO creation when aa==1 and no CRT filter.
-    // In that case we must provide our own FBO; otherwise glBlitFramebuffer
-    // reads from FBO-0 (the raw window backbuffer), which is invalid in libretro.
-    if (renderTarget == 0)
-    {
-        glGenFramebuffers(1, &m_libretrFBO);
-        glBindFramebuffer(GL_FRAMEBUFFER, m_libretrFBO);
-
-        glGenTextures(1, &m_libretrTex);
-        glBindTexture(GL_TEXTURE_2D, m_libretrTex);
-        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8,
-                     totalXRes, totalYRes,
-                     0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
-                               GL_TEXTURE_2D, m_libretrTex, 0);
-
-        glGenRenderbuffers(1, &m_libretrDepth);
-        glBindRenderbuffer(GL_RENDERBUFFER, m_libretrDepth);
-        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8,
-                              totalXRes, totalYRes);
-        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT,
-                                  GL_RENDERBUFFER, m_libretrDepth);
-
-        GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
-        if (status != GL_FRAMEBUFFER_COMPLETE)
-            ErrorLog("[Supermodel] Libretro FBO incomplete: 0x%X", status);
-        else
-            InfoLog("[Supermodel] Libretro FBO created: %ux%u (id=%u)",
-                    totalXRes, totalYRes, m_libretrFBO);
-
-        glBindFramebuffer(GL_FRAMEBUFFER, 0);
-        renderTarget = m_libretrFBO;
-    }
+    GLuint renderTarget = superAA->GetTargetID();
+
+    // Libretro always needs a base-resolution resolved target. With native
+    // supersampling/CRT colour active, SuperAA renders its high-resolution
+    // input down into this FBO. Without that pass, the Model 3 renderers draw
+    // here directly. Never submit SuperAA's high-resolution source FBO to the
+    // frontend: doing so crops the image to its lower-left base-size region.
+    glGenFramebuffers(1, &m_libretrFBO);
+    glBindFramebuffer(GL_FRAMEBUFFER, m_libretrFBO);
+
+    glGenTextures(1, &m_libretrTex);
+    glBindTexture(GL_TEXTURE_2D, m_libretrTex);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8,
+                 totalXRes, totalYRes,
+                 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
+                           GL_TEXTURE_2D, m_libretrTex, 0);
+
+    glGenRenderbuffers(1, &m_libretrDepth);
+    glBindRenderbuffer(GL_RENDERBUFFER, m_libretrDepth);
+    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8,
+                          totalXRes, totalYRes);
+    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT,
+                              GL_RENDERBUFFER, m_libretrDepth);
+
+    GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
+    if (status != GL_FRAMEBUFFER_COMPLETE)
+        ErrorLog("[Supermodel] Libretro FBO incomplete: 0x%X", status);
+    else
+        InfoLog("[Supermodel] Libretro resolved FBO created: %ux%u (id=%u)",
+                totalXRes, totalYRes, m_libretrFBO);
+
+    glBindFramebuffer(GL_FRAMEBUFFER, 0);
+    if (renderTarget != 0)
+        superAA->SetOutputTarget(m_libretrFBO);
+    else
+        renderTarget = m_libretrFBO;
 
     Render2D = new CRender2D(s_runtime_config);
     // Normal desktop builds can include both renderers and select at runtime.
@@ -907,11 +909,10 @@ bool LibretroWrapper::InitGL()
     return InitRenderers();
 }
 
-GLuint LibretroWrapper::getSuperModelFBO() const 
-{
-    GLuint saaFBO = superAA ? superAA->GetTargetID() : 0;
-    return (saaFBO != 0) ? saaFBO : m_libretrFBO;
-}
+GLuint LibretroWrapper::getSuperModelFBO() const
+{
+    return m_libretrFBO;
+}
 
 void LibretroWrapper::SetWidescreen(bool enabled, bool wideBackground)
 {

Src/OSD/libretro/LibretroWrapper.h

@@ -81,8 +81,8 @@ public:
     void ShutDownSupermodel();
     bool InitRenderers();
     bool InitGL();
-    // Returns the actual FBO Supermodel renders into (SuperAA's or our own)
-    GLuint getSuperModelFBO() const;
+    // Returns the base-resolution frame resolved for Libretro submission.
+    GLuint getSuperModelFBO() const;
 
 private:
     float lastEngineMs = 0.0f;

Src/OSD/libretro/libretro.cpp

@@ -285,6 +285,7 @@ CoreOptions g_options = {
    /* renderer_3d          */ Renderer3D::New3D,
    /* quad_rendering       */ false,
    /* crt_colors           */ 0,
+   /* supersampling        */ 1,
    /* upscale_mode          */ 2,
    /* widescreen_mode      */ WidescreenMode::Disabled,
    /* crosshairs           */ 0,
@@ -1099,6 +1100,7 @@ void retro_run(void)
       Renderer3D old_renderer_3d = g_options.renderer_3d;
       bool old_quad_rendering = g_options.quad_rendering;
       int old_crt_colors = g_options.crt_colors;
+      int old_supersampling = g_options.supersampling;
       WidescreenMode old_widescreen_mode = g_options.widescreen_mode;
       int old_upscale_mode = g_options.upscale_mode;
       bool old_legacy_sound_dsp = g_options.legacy_sound_dsp;
@@ -1123,10 +1125,11 @@ void retro_run(void)
 
       if (g_options.renderer_3d != old_renderer_3d ||
           g_options.quad_rendering != old_quad_rendering ||
-          g_options.crt_colors != old_crt_colors)
+          g_options.crt_colors != old_crt_colors ||
+          g_options.supersampling != old_supersampling)
       {
          static const struct retro_message message = {
-            "3D Renderer, Quad Rendering and CRT Colour changes require restarting the content.", 240
+            "Renderer and supersampling changes require restarting the content.", 240
          };
          environ_cb(RETRO_ENVIRONMENT_SET_MESSAGE, (void *)&message);
       }
@@ -1338,7 +1341,14 @@ void retro_run(void)
       glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
 
       glViewport(0, 0, target_w, target_h);
-      glScissor(0, 0, target_w, target_h);
+      // Render2D re-enables the scissor test after clearing its target. The
+      // box is global GL state and must describe the supersampled render FBO,
+      // exactly as standalone scales its scissor by aaValue. Leaving this at
+      // base resolution clips a 2x source to its lower-left quarter before
+      // SuperAA resolves it.
+      const unsigned render_scale = static_cast<unsigned>(
+         std::max(1, wrapper.getAaValue()));
+      glScissor(0, 0, target_w * render_scale, target_h * render_scale);
 
       glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
       glClearDepth(1.0);

Src/OSD/libretro/libretro_core_options.h

@@ -132,6 +132,28 @@ static struct retro_core_option_v2_definition option_defs[] = {
       },
       "0"
    },
+#endif
+#ifdef HAVE_SUPERSAMPLING
+   {
+      "supermodel_supersampling",
+      "Supersampling",
+      NULL,
+      "Render each output pixel from multiple internal samples using Supermodel's native supersampling pass. The scale applies on top of Internal Resolution: 2x uses 4 samples per pixel, 3x uses 9, and 8x uses 64. Higher values can require substantial GPU time and memory. Takes effect after restarting content.",
+      NULL,
+      "video",
+      {
+         { "1", "1x (Disabled, Default)" },
+         { "2", "2x (4 Samples)" },
+         { "3", "3x (9 Samples)" },
+         { "4", "4x (16 Samples)" },
+         { "5", "5x (25 Samples)" },
+         { "6", "6x (36 Samples)" },
+         { "7", "7x (49 Samples)" },
+         { "8", "8x (64 Samples)" },
+         { NULL, NULL },
+      },
+      "1"
+   },
 #endif
    {
       "supermodel_timing_overlay",
@@ -571,6 +593,15 @@ void update_core_options(void)
    g_options.crt_colors = 0;
 #endif
 
+#ifdef HAVE_SUPERSAMPLING
+   g_options.supersampling =
+      atoi(option_get("supermodel_supersampling", "1"));
+   if (g_options.supersampling < 1 || g_options.supersampling > 8)
+      g_options.supersampling = 1;
+#else
+   g_options.supersampling = 1;
+#endif
+
    g_options.upscale_mode = atoi(option_get("supermodel_upscale_mode", "2"));
    if (g_options.upscale_mode < 0 || g_options.upscale_mode > 3)
       g_options.upscale_mode = 2;