Remove extensions and specify shader version

* Fix FBO on OSX

* Remove useless code

* Use GL v2.1 for fonts drawing

* Fix fonts on OSX with GL 2.1

* Rename

* Same thing for GenVertexArrays

* Make fl0w work on OSX

Makefile

@@ -3,7 +3,7 @@ ARCH ?= x86_64
 VERSION ?= dev
 BUNDLENAME = $(APP)-$(OS)-$(ARCH)-$(VERSION)
 
-CORES = atari800 bluemsx swanstation fbneo fceumm gambatte gearsystem genesis_plus_gx handy lutro mednafen_ngp mednafen_pce mednafen_pce_fast mednafen_pcfx mednafen_psx mednafen_saturn mednafen_supergrafx mednafen_vb mednafen_wswan mgba melonds np2kai o2em pcsx_rearmed picodrive pokemini prosystem snes9x stella2014 vecx virtualjaguar
+CORES = ppsspp dolphin atari800 bluemsx swanstation fbneo fceumm gambatte gearsystem genesis_plus_gx handy lutro mednafen_ngp mednafen_pce mednafen_pce_fast mednafen_pcfx mednafen_psx mednafen_saturn mednafen_supergrafx mednafen_vb mednafen_wswan mgba melonds np2kai o2em pcsx_rearmed picodrive pokemini prosystem snes9x stella2014 vecx virtualjaguar
 
 ifeq ($(ARCH), arm)
 	CORES := $(filter-out swanstation,$(CORES))

core/core.go

@@ -201,6 +201,11 @@ func LoadGame(gamePath string) error {
 	log.Println("[Core]: Game loaded: " + gamePath)
 	savefiles.LoadSRAM()
 
+	if state.Core.HWRenderCallback != nil {
+		vid.InitFramebuffer()
+		state.Core.HWRenderCallback.ContextReset()
+	}
+
 	return nil
 }
 

core/environment.go

@@ -143,6 +143,13 @@ func environment(cmd uint32, data unsafe.Pointer) bool {
 		state.Core.SetFrameTimeCallback(data)
 	case libretro.EnvironmentSetAudioCallback:
 		state.Core.SetAudioCallback(data)
+	case libretro.EnvironmentSetHWRender:
+		state.Core.HWRenderCallback = libretro.SetHWRenderCallback(
+			data,
+			vid.CurrentFramebuffer,
+			vid.ProcAddress)
+		log.Println("[Env]: HWContextType:", state.Core.HWRenderCallback.HWContextType)
+		return true
 	case libretro.EnvironmentGetCanDupe:
 		libretro.SetBool(data, true)
 	case libretro.EnvironmentSetPixelFormat:
@@ -151,6 +158,9 @@ func environment(cmd uint32, data unsafe.Pointer) bool {
 		return environmentGetSystemDirectory(data)
 	case libretro.EnvironmentGetSaveDirectory:
 		return environmentGetSaveDirectory(data)
+	case libretro.EnvironmentGetPrefferedHWRender:
+		log.Println("[Env]: EnvironmentGetPrefferedHWRenderer: 1")
+		libretro.SetUint(data, uint(libretro.HWContextOpenGL))
 	case libretro.EnvironmentShutdown:
 		vid.SetShouldClose(true)
 	case libretro.EnvironmentGetCoreOptionsVersion:

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/fatih/structs v1.1.0
 	github.com/go-gl/gl v0.0.0-20211210172815-726fda9656d6
 	github.com/go-gl/glfw/v3.3/glfw v0.0.0-20211213063430-748e38ca8aec
+	github.com/go-gl/mathgl v1.0.0
 	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0
 	github.com/golang/snappy v0.0.4 // indirect
 	github.com/klauspost/compress v1.13.6 // indirect

go.sum

@@ -21,6 +21,8 @@ github.com/go-gl/gl v0.0.0-20211210172815-726fda9656d6 h1:zDw5v7qm4yH7N8C8uWd+8I
 github.com/go-gl/gl v0.0.0-20211210172815-726fda9656d6/go.mod h1:9YTyiznxEY1fVinfM7RvRcjRHbw2xLBJ3AAGIT0I4Nw=
 github.com/go-gl/glfw/v3.3/glfw v0.0.0-20211213063430-748e38ca8aec h1:3FLiRYO6PlQFDpUU7OEFlWgjGD1jnBIVSJ5SYRWk+9c=
 github.com/go-gl/glfw/v3.3/glfw v0.0.0-20211213063430-748e38ca8aec/go.mod h1:tQ2UAYgL5IevRw8kRxooKSPJfGvJ9fJQFa0TUsXzTg8=
+github.com/go-gl/mathgl v1.0.0 h1:t9DznWJlXxxjeeKLIdovCOVJQk/GzDEL7h/h+Ro2B68=
+github.com/go-gl/mathgl v1.0.0/go.mod h1:yhpkQzEiH9yPyxDUGzkmgScbaBVlhC06qodikEM0ZwQ=
 github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 h1:DACJavvAHhabrF08vX0COfcOBJRhZ8lUbR+ZWIs0Y5g=
 github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0/go.mod h1:E/TSTwGwJL78qG/PmXZO1EjYhfJinVAhrmmHX6Z8B9k=
 github.com/golang/snappy v0.0.2/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
@@ -83,6 +85,7 @@ golang.org/x/crypto v0.0.0-20190510104115-cbcb75029529/go.mod h1:yigFU9vqHzYiE8U
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/exp v0.0.0-20190731235908-ec7cb31e5a56/go.mod h1:JhuoJpWY28nO4Vef9tZUw9qufEGTyX1+7lmHxV5q5G4=
 golang.org/x/image v0.0.0-20190227222117-0694c2d4d067/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
+golang.org/x/image v0.0.0-20190321063152-3fc05d484e9f/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
 golang.org/x/image v0.0.0-20190802002840-cff245a6509b/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
 golang.org/x/image v0.0.0-20191009234506-e7c1f5e7dbb8/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
 golang.org/x/image v0.0.0-20211028202545-6944b10bf410 h1:hTftEOvwiOq2+O8k2D5/Q7COC7k5Qcrgc2TFURJYnvQ=

libretro/cfuncs.go

@@ -22,6 +22,14 @@ void bridge_retro_frame_time_callback(retro_frame_time_callback_t f, retro_usec_
 	f(usec);
 }
 
+void bridge_retro_hw_context_reset(retro_hw_context_reset_t f) {
+	f();
+}
+
+void bridge_retro_hw_context_destroy(retro_hw_context_reset_t f) {
+	f();
+}
+
 void bridge_retro_audio_callback(retro_audio_callback_t f) {
 	f();
 }
@@ -168,5 +176,15 @@ int64_t coreGetTimeUsec_cgo() {
 	return coreGetTimeUsec();
 }
 
+uintptr_t coreGetCurrentFramebuffer_cgo() {
+	uintptr_t coreGetCurrentFramebuffer();
+	return coreGetCurrentFramebuffer();
+}
+
+uintptr_t coreGetProcAddress_cgo(const char *sym) {
+	uintptr_t coreGetProcAddress(const char *sym);
+	return coreGetProcAddress(sym);
+}
+
 */
 import "C"

libretro/libretro.go

@@ -33,6 +33,8 @@ void bridge_retro_unload_game(void *f);
 void bridge_retro_run(void *f);
 void bridge_retro_reset(void *f);
 void bridge_retro_frame_time_callback(retro_frame_time_callback_t f, retro_usec_t usec);
+void bridge_retro_hw_context_reset(retro_hw_context_reset_t f);
+void bridge_retro_hw_context_destroy(retro_hw_context_reset_t f);
 void bridge_retro_audio_callback(retro_audio_callback_t f);
 void bridge_retro_audio_set_state(retro_audio_set_state_callback_t f, bool state);
 size_t bridge_retro_get_memory_size(void *f, unsigned id);
@@ -51,6 +53,8 @@ size_t coreAudioSampleBatch_cgo(const int16_t *data, size_t frames);
 int16_t coreInputState_cgo(unsigned port, unsigned device, unsigned index, unsigned id);
 void coreLog_cgo(enum retro_log_level level, const char *msg);
 int64_t coreGetTimeUsec_cgo();
+uintptr_t coreGetCurrentFramebuffer_cgo();
+uintptr_t coreGetProcAddress_cgo(const char *sym);
 */
 import "C"
 import (
@@ -216,6 +220,20 @@ type FrameTimeCallback struct {
 	Reference int64
 }
 
+// HWRenderCallback sets an interface to let a libretro core render with
+// hardware acceleration.
+type HWRenderCallback struct {
+	HWContextType              uint32
+	ContextReset               func()
+	Depth                      bool
+	Stencil                    bool
+	BottomLeftOrigin           bool
+	VersionMajor, VersionMinor uint
+	CacheContext               bool
+	ContextDestroy             func()
+	DebugContext               bool
+}
+
 // AudioCallback stores the audio callback itself and the SetState callback
 type AudioCallback struct {
 	Callback func()
@@ -409,26 +427,48 @@ const (
 	MemoryVideoRAM  = uint32(C.RETRO_MEMORY_VIDEO_RAM)
 )
 
+// Hardware contexts
+const (
+	HWContextNone            = uint32(C.RETRO_HW_CONTEXT_NONE)
+	HWContextOpenGL          = uint32(C.RETRO_HW_CONTEXT_OPENGL)
+	HWContextOpenGLES2       = uint32(C.RETRO_HW_CONTEXT_OPENGLES2)
+	HWContextOpenGLCore      = uint32(C.RETRO_HW_CONTEXT_OPENGL_CORE)
+	HWContextOpenGLES3       = uint32(C.RETRO_HW_CONTEXT_OPENGLES3)
+	HWContextOpenGLESVersion = uint32(C.RETRO_HW_CONTEXT_OPENGLES_VERSION)
+	HWContextVulkan          = uint32(C.RETRO_HW_CONTEXT_VULKAN)
+	HWContextDummy           = uint32(C.RETRO_HW_CONTEXT_DUMMY)
+)
+
+// Pass this to retro_video_refresh_t if rendering to hardware.
+// Passing NULL to retro_video_refresh_t is still a frame dupe as normal.
+var (
+	HWFrameBufferValid = unsafe.Pointer(C.RETRO_HW_FRAME_BUFFER_VALID)
+)
+
 type (
-	environmentFunc      func(uint32, unsafe.Pointer) bool
-	videoRefreshFunc     func(unsafe.Pointer, int32, int32, int32)
-	audioSampleFunc      func(int16, int16)
-	audioSampleBatchFunc func([]byte, int32) int32
-	inputPollFunc        func()
-	inputStateFunc       func(uint, uint32, uint, uint) int16
-	logFunc              func(uint32, string)
-	getTimeUsecFunc      func() int64
+	environmentFunc           func(uint32, unsafe.Pointer) bool
+	videoRefreshFunc          func(unsafe.Pointer, int32, int32, int32)
+	audioSampleFunc           func(int16, int16)
+	audioSampleBatchFunc      func([]byte, int32) int32
+	inputPollFunc             func()
+	inputStateFunc            func(uint, uint32, uint, uint) int16
+	logFunc                   func(uint32, string)
+	getTimeUsecFunc           func() int64
+	getCurrentFramebufferFunc func() uintptr
+	getProcAddressFunc        func(string) uintptr
 )
 
 var (
-	environment      environmentFunc
-	videoRefresh     videoRefreshFunc
-	audioSample      audioSampleFunc
-	audioSampleBatch audioSampleBatchFunc
-	inputPoll        inputPollFunc
-	inputState       inputStateFunc
-	log              logFunc
-	getTimeUsec      getTimeUsecFunc
+	environment           environmentFunc
+	videoRefresh          videoRefreshFunc
+	audioSample           audioSampleFunc
+	audioSampleBatch      audioSampleBatchFunc
+	inputPoll             inputPollFunc
+	inputState            inputStateFunc
+	log                   logFunc
+	getTimeUsec           getTimeUsecFunc
+	getCurrentFramebuffer getCurrentFramebufferFunc
+	getProcAddress        getProcAddressFunc
 )
 
 // Load dynamically loads a libretro core at the given path and returns a Core instance
@@ -490,6 +530,8 @@ func (core *Core) Deinit() {
 	inputState = nil
 	log = nil
 	getTimeUsec = nil
+	getCurrentFramebuffer = nil
+	getProcAddress = nil
 }
 
 // Run runs the game for one video frame.
@@ -721,6 +763,16 @@ func coreGetTimeUsec() C.uint64_t {
 	return C.uint64_t(getTimeUsec())
 }
 
+//export coreGetCurrentFramebuffer
+func coreGetCurrentFramebuffer() C.uintptr_t {
+	return C.uintptr_t(getCurrentFramebuffer())
+}
+
+//export coreGetProcAddress
+func coreGetProcAddress(sym *C.char) C.uintptr_t {
+	return C.uintptr_t(getProcAddress(C.GoString(sym)))
+}
+
 // SetData is a setter for the data of a GameInfo type
 func (gi *GameInfo) SetData(bytes []byte) {
 	cstr := C.CString(string(bytes))
@@ -883,6 +935,38 @@ func (core *Core) SetFrameTimeCallback(data unsafe.Pointer) {
 	core.FrameTimeCallback = ftc
 }
 
+// SetHWRenderCallback is an environment callback helper to set the HWRenderCallback
+func SetHWRenderCallback(
+	data unsafe.Pointer,
+	currentFramebuffer getCurrentFramebufferFunc,
+	procAddress getProcAddressFunc,
+) *HWRenderCallback {
+	c := (*C.struct_retro_hw_render_callback)(data)
+	hwrc := HWRenderCallback{}
+	hwrc.HWContextType = uint32(c.context_type)
+
+	getCurrentFramebuffer = currentFramebuffer
+	getProcAddress = procAddress
+	c.get_current_framebuffer = (C.retro_hw_get_current_framebuffer_t)(C.coreGetCurrentFramebuffer_cgo)
+	c.get_proc_address = (C.retro_hw_get_proc_address_t)(C.coreGetProcAddress_cgo)
+
+	hwrc.ContextReset = func() {
+		C.bridge_retro_hw_context_reset((C.retro_hw_context_reset_t)(c.context_reset))
+	}
+
+	hwrc.Depth = bool(c.depth)
+	hwrc.Stencil = bool(c.stencil)
+	hwrc.BottomLeftOrigin = bool(c.bottom_left_origin)
+	hwrc.VersionMajor = uint(c.version_major)
+	hwrc.VersionMinor = uint(c.version_minor)
+	hwrc.CacheContext = bool(c.cache_context)
+	hwrc.ContextDestroy = func() {
+		C.bridge_retro_hw_context_destroy((C.retro_hw_context_reset_t)(c.context_destroy))
+	}
+	hwrc.DebugContext = bool(c.debug_context)
+	return &hwrc
+}
+
 // SetAudioCallback is an environment callback helper to set the AudioCallback
 func (core *Core) SetAudioCallback(data unsafe.Pointer) {
 	c := *(*C.struct_retro_audio_callback)(data)

libretro/libretro_core.go

@@ -31,6 +31,7 @@ type Core struct {
 	AudioCallback       *AudioCallback
 	FrameTimeCallback   *FrameTimeCallback
 	DiskControlCallback *DiskControlCallback
+	HWRenderCallback    *HWRenderCallback
 
 	MemoryMap []MemoryDescriptor
 }

menu/thumbnail.go

@@ -7,7 +7,7 @@ import (
 	"path/filepath"
 	"strings"
 
-	"github.com/go-gl/gl/v2.1/gl"
+	"github.com/go-gl/gl/v4.1-core/gl"
 	"github.com/libretro/ludo/settings"
 	"github.com/libretro/ludo/video"
 )

video/default_vert_shader.go

@@ -19,8 +19,10 @@ COMPAT_ATTRIBUTE vec2 vertTexCoord;
 
 COMPAT_VARYING vec2 fragTexCoord;
 
+uniform mat4 MVP;
+
 void main() {
   fragTexCoord = vertTexCoord;
-  gl_Position = vec4(vert, 0.0, 1.0);
+  gl_Position = vec4(vert, 0.0, 1.0) * MVP;
 }
 ` + "\x00"

video/font.go

@@ -8,7 +8,7 @@ import (
 	"io/ioutil"
 	"os"
 
-	"github.com/go-gl/gl/v2.1/gl"
+	"github.com/go-gl/gl/v4.1-core/gl"
 	"github.com/golang/freetype"
 	"github.com/golang/freetype/truetype"
 	"golang.org/x/image/font"
@@ -174,22 +174,14 @@ func LoadTrueTypeFont(program uint32, r io.Reader, scale int32, low, high rune,
 		f.fontChar = append(f.fontChar, char)
 	}
 
-	// Generate texture
-	gl.GenTextures(1, &f.textureID)
-	gl.BindTexture(gl.TEXTURE_2D, f.textureID)
-	gl.PixelStorei(gl.UNPACK_ALIGNMENT, 1)
-	gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_LINEAR)
-	gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
-
-	gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, int32(rgba.Rect.Dx()), int32(rgba.Rect.Dy()), 0, gl.RGBA, gl.UNSIGNED_BYTE, gl.Ptr(rgba.Pix))
-
-	gl.GenerateMipmap(gl.TEXTURE_2D)
-	gl.BindTexture(gl.TEXTURE_2D, 0)
+	textureUniform := gl.GetUniformLocation(f.program, gl.Str("Texture\x00"))
+	gl.Uniform1i(textureUniform, 0)
 
 	// Configure VAO/VBO for texture quads
 	genVertexArrays(1, &f.vao)
-	gl.GenBuffers(1, &f.vbo)
 	bindVertexArray(f.vao)
+
+	gl.GenBuffers(1, &f.vbo)
 	gl.BindBuffer(gl.ARRAY_BUFFER, f.vbo)
 
 	vertAttrib := uint32(gl.GetAttribLocation(f.program, gl.Str("vert\x00")))
@@ -200,6 +192,16 @@ func LoadTrueTypeFont(program uint32, r io.Reader, scale int32, low, high rune,
 	gl.EnableVertexAttribArray(texCoordAttrib)
 	gl.VertexAttribPointerWithOffset(texCoordAttrib, 2, gl.FLOAT, false, 4*4, 2*4)
 
+	// Generate texture
+	gl.ActiveTexture(gl.TEXTURE0)
+	gl.GenTextures(1, &f.textureID)
+	gl.BindTexture(gl.TEXTURE_2D, f.textureID)
+	gl.PixelStorei(gl.UNPACK_ALIGNMENT, 1)
+	gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_LINEAR)
+	gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
+	gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, int32(rgba.Rect.Dx()), int32(rgba.Rect.Dy()), 0, gl.RGBA, gl.UNSIGNED_BYTE, gl.Ptr(rgba.Pix))
+	gl.GenerateMipmap(gl.TEXTURE_2D)
+
 	gl.BindBuffer(gl.ARRAY_BUFFER, 0)
 	bindVertexArray(0)
 
@@ -224,8 +226,7 @@ func LoadFont(file string, scale int32, windowWidth int, windowHeight int) (*Fon
 	gl.UseProgram(program)
 
 	// Set screen resolution
-	resUniform := gl.GetUniformLocation(program, gl.Str("resolution\x00"))
-	gl.Uniform2f(resUniform, float32(windowWidth), float32(windowHeight))
+	gl.Uniform2f(gl.GetUniformLocation(program, gl.Str("resolution\x00")), float32(windowWidth), float32(windowHeight))
 
 	return LoadTrueTypeFont(program, fd, scale, 32, 256, LeftToRight)
 }
@@ -253,15 +254,6 @@ func (f *Font) Printf(x, y float32, scale float32, fs string, argv ...interface{
 
 	lowChar := rune(32)
 
-	// Setup blending mode
-	gl.Enable(gl.BLEND)
-	gl.BlendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
-
-	// Activate corresponding render state
-	gl.UseProgram(f.program)
-	// Set text color
-	gl.Uniform4f(gl.GetUniformLocation(f.program, gl.Str("textColor\x00")), f.color.R, f.color.G, f.color.B, f.color.A)
-
 	var coords []point
 
 	// Iterate through all characters in string
@@ -302,6 +294,10 @@ func (f *Font) Printf(x, y float32, scale float32, fs string, argv ...interface{
 		x += float32((ch.advance >> 6)) * scale // Bitshift by 6 to get value in pixels (2^6 = 64 (divide amount of 1/64th pixels by 64 to get amount of pixels))
 	}
 
+	gl.UseProgram(f.program)
+	gl.Uniform4f(gl.GetUniformLocation(f.program, gl.Str("color\x00")), f.color.R, f.color.G, f.color.B, f.color.A)
+	gl.Enable(gl.BLEND)
+	gl.BlendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
 	bindVertexArray(f.vao)
 	gl.ActiveTexture(gl.TEXTURE0)
 	gl.BindTexture(gl.TEXTURE_2D, f.textureID)

video/font_frag_shader.go

@@ -6,7 +6,7 @@ var fontFragmentShader = `
 #define COMPAT_ATTRIBUTE in
 #define COMPAT_TEXTURE texture
 #define COMPAT_FRAGCOLOR FragColor
-out vec4 FragColor;
+out vec4 COMPAT_FRAGCOLOR;
 #else
 #define COMPAT_VARYING varying
 #define COMPAT_ATTRIBUTE attribute
@@ -14,12 +14,13 @@ out vec4 FragColor;
 #define COMPAT_FRAGCOLOR gl_FragColor
 #endif
 
-uniform sampler2D tex;
-uniform vec4 textColor;
+uniform sampler2D Texture;
+uniform vec4 color;
+
 COMPAT_VARYING vec2 fragTexCoord;
 
 void main() {
-	vec4 sampled = vec4(1.0, 1.0, 1.0, COMPAT_TEXTURE(tex, fragTexCoord).r);
-	COMPAT_FRAGCOLOR = min(textColor, vec4(1.0, 1.0, 1.0, 1.0)) * sampled;
+	vec4 sampled = vec4(1.0, 1.0, 1.0, COMPAT_TEXTURE(Texture, fragTexCoord).r);
+	COMPAT_FRAGCOLOR = min(color, vec4(1.0, 1.0, 1.0, 1.0)) * sampled;
 }
 ` + "\x00"

video/gfx.go

@@ -5,7 +5,7 @@ import (
 	"image/draw"
 	"os"
 
-	"github.com/go-gl/gl/v2.1/gl"
+	"github.com/go-gl/gl/v4.1-core/gl"
 )
 
 // Color is an RGBA type that we use in the menu

video/screenshot.go

@@ -7,7 +7,7 @@ import (
 	"path/filepath"
 
 	"github.com/disintegration/imaging"
-	"github.com/go-gl/gl/v2.1/gl"
+	"github.com/go-gl/gl/v4.1-core/gl"
 
 	"github.com/libretro/ludo/settings"
 	"github.com/libretro/ludo/state"

video/shader_utils.go

@@ -4,7 +4,8 @@ import (
 	"fmt"
 	"strings"
 
-	"github.com/go-gl/gl/v2.1/gl"
+	"github.com/go-gl/gl/v4.1-core/gl"
+	"github.com/go-gl/mathgl/mgl32"
 )
 
 func newProgram(vertexShaderSource, fragmentShaderSource string) (uint32, error) {
@@ -39,12 +40,25 @@ func newProgram(vertexShaderSource, fragmentShaderSource string) (uint32, error)
 	gl.DeleteShader(vertexShader)
 	gl.DeleteShader(fragmentShader)
 
+	// Only the core rendering code uses MVPs so we set it to identity
+	// to avoid issues with other parts of the program
+	gl.UseProgram(program)
+	mvp := gl.GetUniformLocation(program, gl.Str("MVP\x00"))
+
+	if mvp != -1 {
+		IdentityMatrix := mgl32.Ident4()
+		gl.UniformMatrix4fv(mvp, 1, false, &IdentityMatrix[0])
+	}
+	gl.UseProgram(0)
+
 	return program, nil
 }
 
 func compileShader(source string, shaderType uint32) (uint32, error) {
 	shader := gl.CreateShader(shaderType)
 
+	source = "#version 410\n" + source
+
 	csources, free := gl.Strs(source)
 	gl.ShaderSource(shader, 1, csources, nil)
 	free()

video/video.go

@@ -4,12 +4,14 @@
 package video
 
 import (
+	"fmt"
 	"log"
 	"path/filepath"
 	"unsafe"
 
-	"github.com/go-gl/gl/v2.1/gl"
+	"github.com/go-gl/gl/v4.1-core/gl"
 	"github.com/go-gl/glfw/v3.3/glfw"
+	"github.com/go-gl/mathgl/mgl32"
 	"github.com/libretro/ludo/libretro"
 	"github.com/libretro/ludo/settings"
 	"github.com/libretro/ludo/state"
@@ -33,6 +35,10 @@ type Video struct {
 	vao                  uint32
 	vbo                  uint32
 	texID                uint32
+	fboID                uint32
+	rboID                uint32
+	identityMat          mgl32.Mat4 // just a cache
+	orthoMat             mgl32.Mat4
 
 	pitch         int32  // pitch set by the refresh callback
 	pixFmt        uint32 // format set by the environment callback
@@ -45,6 +51,7 @@ type Video struct {
 // Init instanciates the video package
 func Init(fullscreen bool) *Video {
 	vid := &Video{}
+	vid.identityMat = mgl32.Ident4()
 	vid.Configure(fullscreen)
 	return vid
 }
@@ -52,6 +59,14 @@ func Init(fullscreen bool) *Video {
 // Reconfigure destroys and recreates the window with new attributes
 func (video *Video) Reconfigure(fullscreen bool) {
 	if video.Window != nil {
+		// This is the expected frontend behavior and Flycast requires this
+		// for fullscreen toggling to work, but ppsspp breaks. OTOH, ppsspp
+		// breaks in those situations even if we don't call context_destroy
+		// so ignore it.
+		hw := state.Core.HWRenderCallback
+		if state.CoreRunning && hw != nil && hw.ContextDestroy != nil {
+			state.Core.HWRenderCallback.ContextDestroy()
+		}
 		video.Window.Destroy()
 	}
 	video.Configure(fullscreen)
@@ -97,6 +112,11 @@ func (video *Video) Configure(fullscreen bool) {
 		height = 240 * 2
 	}
 
+	glfw.WindowHint(glfw.ContextVersionMajor, 4)
+	glfw.WindowHint(glfw.ContextVersionMinor, 1)
+	glfw.WindowHint(glfw.OpenGLProfile, glfw.OpenGLCoreProfile)
+	glfw.WindowHint(glfw.OpenGLForwardCompatible, glfw.True)
+
 	var err error
 	video.Window, err = glfw.CreateWindow(width, height, "Ludo", m, nil)
 	if err != nil {
@@ -115,6 +135,12 @@ func (video *Video) Configure(fullscreen bool) {
 		panic(err)
 	}
 
+	version := gl.GoStr(gl.GetString(gl.VERSION))
+	fmt.Println("OpenGL version", version)
+
+	shversion := gl.GoStr(gl.GetString(gl.SHADING_LANGUAGE_VERSION))
+	fmt.Println("OpenGL shading version", shversion)
+
 	fbw, fbh := video.Window.GetFramebufferSize()
 
 	// LoadFont (fontfile, font scale, window width, window height)
@@ -167,6 +193,7 @@ func (video *Video) Configure(fullscreen bool) {
 
 	video.UpdateFilter(settings.Current.VideoFilter)
 
+	gl.UseProgram(video.program)
 	textureUniform := gl.GetUniformLocation(video.program, gl.Str("Texture\x00"))
 	gl.Uniform1i(textureUniform, 0)
 
@@ -193,20 +220,27 @@ func (video *Video) Configure(fullscreen bool) {
 		video.bpp = 2
 	}
 
-	gl.GenTextures(1, &video.texID)
-
-	gl.ActiveTexture(gl.TEXTURE0)
-	if video.texID == 0 && state.Verbose {
-		log.Println("[Video]: Failed to create the vid texture")
+	if video.Geom.MaxWidth == 0 || video.Geom.MaxHeight == 0 {
+		video.Geom.MaxWidth = video.Geom.BaseWidth
+		video.Geom.MaxHeight = video.Geom.BaseHeight
 	}
 
+	gl.GenTextures(1, &video.texID)
+	if video.texID == 0 && state.Verbose {
+		log.Fatalln("[Video]: Failed to create the vid texture")
+	}
+
+	gl.ActiveTexture(gl.TEXTURE0)
 	gl.BindTexture(gl.TEXTURE_2D, video.texID)
+	gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA8, int32(video.Geom.MaxWidth), int32(video.Geom.MaxHeight), 0, video.pixType, video.pixFmt, nil)
 
 	video.UpdateFilter(settings.Current.VideoFilter)
 
-	video.coreRatioViewport(fbw, fbh)
+	video.coreRatioViewport(fbw, fbh, video.Geom.BaseWidth, video.Geom.BaseHeight)
 
-	if e := gl.GetError(); e != gl.NO_ERROR {
+	bindVertexArray(0)
+
+	for e := gl.GetError(); e != gl.NO_ERROR; e = gl.NO_ERROR {
 		log.Printf("[Video] OpenGL error: %d\n", e)
 	}
 }
@@ -219,6 +253,7 @@ func (video *Video) Configure(fullscreen bool) {
 // CRT: zfast-crt
 // LCD: zfast-lcd
 func (video *Video) UpdateFilter(filter string) {
+	gl.ActiveTexture(gl.TEXTURE0)
 	gl.BindTexture(gl.TEXTURE_2D, video.texID)
 	switch filter {
 	case "Smooth":
@@ -247,8 +282,9 @@ func (video *Video) UpdateFilter(filter string) {
 	gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
 	gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
 	gl.UseProgram(video.program)
-	gl.Uniform2f(gl.GetUniformLocation(video.program, gl.Str("TextureSize\x00")), float32(video.width), float32(video.height))
+	gl.Uniform2f(gl.GetUniformLocation(video.program, gl.Str("TextureSize\x00")), float32(video.Geom.MaxWidth), float32(video.Geom.MaxHeight))
 	gl.Uniform2f(gl.GetUniformLocation(video.program, gl.Str("InputSize\x00")), float32(video.width), float32(video.height))
+	gl.UseProgram(0)
 }
 
 // SetPixelFormat is a callback passed to the libretro implementation.
@@ -298,7 +334,7 @@ func (video *Video) ResetRot() {
 
 // coreRatioViewport configures the vertex array to display the game at the center of the window
 // while preserving the original ascpect ratio of the game or core
-func (video *Video) coreRatioViewport(fbWidth int, fbHeight int) (x, y, w, h float32) {
+func (video *Video) coreRatioViewport(fbWidth, fbHeight, clipWidth, clipHeight int) (x, y, w, h float32) {
 	// Scale the content to fit in the viewport.
 	fbw := float32(fbWidth)
 	fbh := float32(fbHeight)
@@ -321,6 +357,12 @@ func (video *Video) coreRatioViewport(fbWidth int, fbHeight int) (x, y, w, h flo
 	y = (fbh - h) / 2
 
 	va := video.vertexArray(x, y, w, h, 1.0)
+
+	va[3] = float32(clipHeight) / float32(video.Geom.MaxHeight)
+	va[10] = float32(clipWidth) / float32(video.Geom.MaxWidth)
+	va[11] = va[3]
+	va[14] = va[10]
+
 	va = rotateUV(va, video.rot)
 	gl.BindBuffer(gl.ARRAY_BUFFER, video.vbo)
 	gl.BufferData(gl.ARRAY_BUFFER, len(va)*4, gl.Ptr(va), gl.STATIC_DRAW)
@@ -336,36 +378,64 @@ func (video *Video) ResizeViewport() {
 
 // Render the current frame
 func (video *Video) Render() {
+	// Render directly to the screen
+	bindBackbuffer()
+
+	// We can't trust the core to leave the OpenGL in the same state as
+	// before retro_run() was called so we restore some state manually.
+	gl.Disable(gl.DEPTH_TEST)
+	gl.Disable(gl.CULL_FACE)
+	gl.Disable(gl.DITHER)
+	gl.Disable(gl.STENCIL_TEST)
+	gl.Disable(gl.BLEND)
+	gl.BlendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
+	gl.BlendEquation(gl.FUNC_ADD)
+	gl.Enable(gl.TEXTURE_2D)
+
+	video.ResizeViewport()
+
 	if !state.CoreRunning {
 		gl.ClearColor(1, 1, 1, 1)
 		gl.Clear(gl.COLOR_BUFFER_BIT)
 		return
 	}
+
 	gl.ClearColor(0, 0, 0, 1)
 	gl.Clear(gl.COLOR_BUFFER_BIT)
 
 	// Early return to not render the first frame of a newly loaded game with the
 	// previous game pitch. A sane pitch must be set by video.Refresh first.
-	if video.pitch == 0 {
+	if state.Core.HWRenderCallback == nil && video.pitch == 0 {
 		return
 	}
 
 	fbw, fbh := video.Window.GetFramebufferSize()
-	_, _, w, h := video.coreRatioViewport(fbw, fbh)
+	_, _, w, h := video.coreRatioViewport(fbw, fbh, int(video.width), int(video.height))
 
 	gl.UseProgram(video.program)
 	gl.Uniform2f(gl.GetUniformLocation(video.program, gl.Str("OutputSize\x00")), w, h)
 
-	bindVertexArray(video.vao)
+	if state.Core.HWRenderCallback != nil {
+		gl.UniformMatrix4fv(gl.GetUniformLocation(video.program, gl.Str("MVP\x00")), 1, false, &video.orthoMat[0])
+	}
 
+	gl.ActiveTexture(gl.TEXTURE0)
 	gl.BindTexture(gl.TEXTURE_2D, video.texID)
 	gl.BindBuffer(gl.ARRAY_BUFFER, video.vbo)
 
+	bindVertexArray(video.vao)
 	gl.DrawArrays(gl.TRIANGLE_STRIP, 0, 4)
+	bindVertexArray(0)
+
+	// Reset MVP to identity to avoid menu issues
+	gl.UniformMatrix4fv(gl.GetUniformLocation(video.program, gl.Str("MVP\x00")), 1, false, &video.identityMat[0])
+	gl.UseProgram(0)
 }
 
 // Refresh the texture framebuffer
 func (video *Video) Refresh(data unsafe.Pointer, width int32, height int32, pitch int32) {
+	bindBackbuffer()
+
 	video.width = width
 	video.height = height
 	video.pitch = pitch
@@ -374,13 +444,28 @@ func (video *Video) Refresh(data unsafe.Pointer, width int32, height int32, pitc
 	gl.PixelStorei(gl.UNPACK_ROW_LENGTH, video.pitch/video.bpp)
 
 	gl.UseProgram(video.program)
-	gl.Uniform2f(gl.GetUniformLocation(video.program, gl.Str("TextureSize\x00")), float32(width), float32(height))
+
+	gl.ActiveTexture(gl.TEXTURE0)
+	gl.BindTexture(gl.TEXTURE_2D, video.texID)
+
+	if data != nil && data != libretro.HWFrameBufferValid {
+		gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA8, int32(video.Geom.MaxWidth), int32(video.Geom.MaxHeight), 0, video.pixType, video.pixFmt, data)
+	}
+
+	gl.Uniform2f(gl.GetUniformLocation(video.program, gl.Str("TextureSize\x00")), float32(video.Geom.MaxWidth), float32(video.Geom.MaxHeight))
 	gl.Uniform2f(gl.GetUniformLocation(video.program, gl.Str("InputSize\x00")), float32(width), float32(height))
 
-	if data == nil {
-		return
-	}
-	gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA8, width, height, 0, video.pixType, video.pixFmt, data)
+	gl.UseProgram(0)
+}
+
+// CurrentFramebuffer returns the current FBO ID
+func (video *Video) CurrentFramebuffer() uintptr {
+	return uintptr(video.fboID)
+}
+
+// ProcAddress returns the address of the proc from GLFW
+func (video *Video) ProcAddress(procName string) uintptr {
+	return uintptr(glfw.GetProcAddress(procName))
 }
 
 // SetRotation rotates the game image as requested by the core

video/video_darwin.go

@@ -1,15 +1,80 @@
+//go:build darwin
 // +build darwin
 
 package video
 
 import (
-	"github.com/go-gl/gl/v2.1/gl"
+	"log"
+
+	"github.com/go-gl/gl/v4.1-core/gl"
+	"github.com/go-gl/mathgl/mgl32"
+	"github.com/libretro/ludo/state"
 )
 
+// InitFramebuffer initializes and configures the video frame buffer based on
+// informations from the HWRenderCallback of the libretro core.
+func (video *Video) InitFramebuffer() {
+	width := int32(video.Geom.MaxWidth)
+	height := int32(video.Geom.MaxHeight)
+
+	log.Printf("[Video]: Initializing HW render (%v x %v).\n", width, height)
+
+	gl.ActiveTexture(gl.TEXTURE0)
+	gl.BindTexture(gl.TEXTURE_2D, video.texID)
+	gl.TexStorage2D(gl.TEXTURE_2D, 1, gl.RGBA8, width, height)
+
+	gl.GenFramebuffers(1, &video.fboID)
+	gl.BindFramebuffer(gl.FRAMEBUFFER, video.fboID)
+	gl.FramebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, video.texID, 0)
+
+	hw := state.Core.HWRenderCallback
+	if hw.Depth {
+		gl.GenRenderbuffers(1, &video.rboID)
+		gl.BindRenderbuffer(gl.RENDERBUFFER, video.rboID)
+		format := gl.DEPTH_COMPONENT16
+		if hw.Stencil {
+			format = gl.DEPTH24_STENCIL8
+		}
+		gl.RenderbufferStorage(gl.RENDERBUFFER, uint32(format), width, height)
+		gl.BindRenderbuffer(gl.RENDERBUFFER, 0)
+
+		if hw.Stencil {
+			gl.FramebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.RENDERBUFFER, video.rboID)
+		} else {
+			gl.FramebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, video.rboID)
+		}
+	}
+
+	// Default origin is top left
+	video.orthoMat = mgl32.Ortho2D(-1, 1, -1, 1)
+	if hw.BottomLeftOrigin {
+		video.orthoMat = mgl32.Ortho2D(-1, 1, 1, -1)
+	}
+
+	if st := gl.CheckFramebufferStatus(gl.FRAMEBUFFER); st != gl.FRAMEBUFFER_COMPLETE {
+		log.Fatalf("[Video] Framebuffer is not complete. Error: %v\n", st)
+	}
+
+	bindBackbuffer()
+
+	gl.ClearColor(0, 0, 0, 1)
+	if hw.Depth && hw.Stencil {
+		gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT | gl.STENCIL_BUFFER_BIT)
+	} else if hw.Depth {
+		gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
+	} else {
+		gl.Clear(gl.COLOR_BUFFER_BIT)
+	}
+}
+
+func bindBackbuffer() {
+	gl.BindFramebuffer(gl.FRAMEBUFFER, 0)
+}
+
 func genVertexArrays(n int32, arrays *uint32) {
-	gl.GenVertexArraysAPPLE(n, arrays)
+	gl.GenVertexArrays(n, arrays)
 }
 
 func bindVertexArray(array uint32) {
-	gl.BindVertexArrayAPPLE(array)
+	gl.BindVertexArray(array)
 }

video/video_notdarwin.go

@@ -1,11 +1,76 @@
+//go:build !darwin
 // +build !darwin
 
 package video
 
 import (
-	"github.com/go-gl/gl/v2.1/gl"
+	"log"
+
+	"github.com/go-gl/gl/v4.1-core/gl"
+	"github.com/go-gl/mathgl/mgl32"
+	"github.com/libretro/ludo/state"
 )
 
+// InitFramebuffer initializes and configures the video frame buffer based on
+// informations from the HWRenderCallback of the libretro core.
+func (video *Video) InitFramebuffer() {
+	width := int32(video.Geom.MaxWidth)
+	height := int32(video.Geom.MaxHeight)
+
+	log.Printf("[Video]: Initializing HW render (%v x %v).\n", width, height)
+
+	gl.ActiveTexture(gl.TEXTURE0)
+	gl.BindTexture(gl.TEXTURE_2D, video.texID)
+	gl.TexStorage2D(gl.TEXTURE_2D, 1, gl.RGBA8, width, height)
+
+	gl.GenFramebuffers(1, &video.fboID)
+	gl.BindFramebuffer(gl.FRAMEBUFFER, video.fboID)
+	gl.FramebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, video.texID, 0)
+
+	hw := state.Core.HWRenderCallback
+	if hw.Depth {
+		gl.GenRenderbuffers(1, &video.rboID)
+		gl.BindRenderbuffer(gl.RENDERBUFFER, video.rboID)
+		format := gl.DEPTH_COMPONENT16
+		if hw.Stencil {
+			format = gl.DEPTH24_STENCIL8
+		}
+		gl.RenderbufferStorage(gl.RENDERBUFFER, uint32(format), width, height)
+		gl.BindRenderbuffer(gl.RENDERBUFFER, 0)
+
+		if hw.Stencil {
+			gl.FramebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.RENDERBUFFER, video.rboID)
+		} else {
+			gl.FramebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, video.rboID)
+		}
+	}
+
+	// Default origin is top left
+	video.orthoMat = mgl32.Ortho2D(-1, 1, -1, 1)
+	if hw.BottomLeftOrigin {
+		video.orthoMat = mgl32.Ortho2D(-1, 1, 1, -1)
+	}
+
+	if st := gl.CheckFramebufferStatus(gl.FRAMEBUFFER); st != gl.FRAMEBUFFER_COMPLETE {
+		log.Fatalf("[Video] Framebuffer is not complete. Error: %v\n", st)
+	}
+
+	bindBackbuffer()
+
+	gl.ClearColor(0, 0, 0, 1)
+	if hw.Depth && hw.Stencil {
+		gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT | gl.STENCIL_BUFFER_BIT)
+	} else if hw.Depth {
+		gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
+	} else {
+		gl.Clear(gl.COLOR_BUFFER_BIT)
+	}
+}
+
+func bindBackbuffer() {
+	gl.BindFramebuffer(gl.FRAMEBUFFER, 0)
+}
+
 func genVertexArrays(n int32, arrays *uint32) {
 	gl.GenVertexArrays(n, arrays)
 }