Clean up the 3D renderer for enhanced flexibility (#1895)

* Give `GPU2D::Unit` a virtual destructor

- Undefined behavior avoided!

* Add an `array2d` alias

* Move various parts of `GPU2D::SoftRenderer` to `constexpr`

- `SoftRenderer::MosaicTable` is now initialized at compile-time
- Most of the `SoftRenderer::Color*` functions are now `constexpr`
- The aforementioned functions are used with a constant value in at least one place, so they'll be at least partially computed at compile-time

* Generalize `GLRenderer::PrepareCaptureFrame`

- Declare it in the base `Renderer3D` class, but make it empty

* Remove unneeded `virtual` specifiers

* Store `Framebuffer`'s memory in `unique_ptr`s

- Reduce the risk of leaks this way

* Clean up how `GLCompositor` is initialized

- Return it as an `std::optional` instead of a `std::unique_ptr`
- Make `GLCompositor` movable
- Replace `GLCompositor`'s plain arrays with `std::array` to simplify moving

* Pass `GPU` to `GLCompositor`'s important functions instead of passing it to the constructor

* Move `GLCompositor` to be a field within `GLRenderer`

- Some methods were moved up and made `virtual`

* Fix some linker errors

* Set the renderer in the frontend

* Remove unneeded `virtual` specifiers

* Remove `RenderSettings` in favor of just exposing the relevant member variables

* Update the frontend to accommodate the core changes

* Add `constexpr` and `const` to places in the interpolator

* Qualify references to `size_t`

* Construct the `optional` directly instead of using `make_optional`

- It makes the Linux build choke
- I think it's because `GLCompositor`'s constructor is `private`

1 files changed, 85 insertions, 25 deletions

diff --git a/src/GPU_OpenGL.cpp b/src/GPU_OpenGL.cpp
index 2db3810..2e2857c 100644
--- a/src/GPU_OpenGL.cpp
+++ b/src/GPU_OpenGL.cpp
@@ -33,13 +33,13 @@ namespace melonDS
 
 using namespace OpenGL;
 
-std::unique_ptr<GLCompositor> GLCompositor::New(melonDS::GPU& gpu) noexcept
+std::optional<GLCompositor> GLCompositor::New() noexcept
 {
     assert(glBindAttribLocation != nullptr);
 
     std::array<GLuint, 3> CompShader {};
     if (!OpenGL::BuildShaderProgram(kCompositorVS, kCompositorFS_Nearest, &CompShader[0], "CompositorShader"))
-        return nullptr;
+        return std::nullopt;
 
     glBindAttribLocation(CompShader[2], 0, "vPosition");
     glBindAttribLocation(CompShader[2], 1, "vTexcoord");
@@ -48,12 +48,12 @@ std::unique_ptr<GLCompositor> GLCompositor::New(melonDS::GPU& gpu) noexcept
     if (!OpenGL::LinkShaderProgram(CompShader.data()))
         // OpenGL::LinkShaderProgram already deletes the shader program object
         // if linking the shaders together failed.
-        return nullptr;
+        return std::nullopt;
 
-    return std::unique_ptr<GLCompositor>(new GLCompositor(CompShader, gpu));
+    return { GLCompositor(CompShader) };
 }
 
-GLCompositor::GLCompositor(std::array<GLuint, 3> compShader, melonDS::GPU& gpu) noexcept : CompShader(compShader), GPU(gpu)
+GLCompositor::GLCompositor(std::array<GLuint, 3> compShader) noexcept : CompShader(compShader)
 {
     CompScaleLoc = glGetUniformLocation(CompShader[2], "u3DScale");
     Comp3DXPosLoc = glGetUniformLocation(CompShader[2], "u3DXPos");
@@ -92,7 +92,7 @@ GLCompositor::GLCompositor(std::array<GLuint, 3> compShader, melonDS::GPU& gpu)
 
     glGenBuffers(1, &CompVertexBufferID);
     glBindBuffer(GL_ARRAY_BUFFER, CompVertexBufferID);
-    glBufferData(GL_ARRAY_BUFFER, sizeof(CompVertices), CompVertices, GL_STATIC_DRAW);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(CompVertices), &CompVertices[0], GL_STATIC_DRAW);
 
     glGenVertexArrays(1, &CompVertexArrayID);
     glBindVertexArray(CompVertexArrayID);
@@ -101,7 +101,7 @@ GLCompositor::GLCompositor(std::array<GLuint, 3> compShader, melonDS::GPU& gpu)
     glEnableVertexAttribArray(1); // texcoord
     glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(CompVertex), (void*)(offsetof(CompVertex, Texcoord)));
 
-    glGenFramebuffers(2, CompScreenOutputFB);
+    glGenFramebuffers(CompScreenOutputFB.size(), &CompScreenOutputFB[0]);
 
     glGenTextures(1, &CompScreenInputTex);
     glActiveTexture(GL_TEXTURE0);
@@ -112,10 +112,10 @@ GLCompositor::GLCompositor(std::array<GLuint, 3> compShader, melonDS::GPU& gpu)
     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(2, CompScreenOutputTex);
-    for (int i = 0; i < 2; i++)
+    glGenTextures(CompScreenOutputTex.size(), &CompScreenOutputTex[0]);
+    for (GLuint i : CompScreenOutputTex)
     {
-        glBindTexture(GL_TEXTURE_2D, CompScreenOutputTex[i]);
+        glBindTexture(GL_TEXTURE_2D, 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);
@@ -129,9 +129,9 @@ GLCompositor::~GLCompositor()
 {
     assert(glDeleteFramebuffers != nullptr);
 
-    glDeleteFramebuffers(2, CompScreenOutputFB);
+    glDeleteFramebuffers(CompScreenOutputFB.size(), &CompScreenOutputFB[0]);
     glDeleteTextures(1, &CompScreenInputTex);
-    glDeleteTextures(2, CompScreenOutputTex);
+    glDeleteTextures(CompScreenOutputTex.size(), &CompScreenOutputTex[0]);
 
     glDeleteVertexArrays(1, &CompVertexArrayID);
     glDeleteBuffers(1, &CompVertexBufferID);
@@ -139,14 +139,75 @@ GLCompositor::~GLCompositor()
     OpenGL::DeleteShaderProgram(CompShader.data());
 }
 
-void GLCompositor::Reset()
+
+GLCompositor::GLCompositor(GLCompositor&& other) noexcept :
+    Scale(other.Scale),
+    ScreenH(other.ScreenH),
+    ScreenW(other.ScreenW),
+    CompScaleLoc(other.CompScaleLoc),
+    Comp3DXPosLoc(other.Comp3DXPosLoc),
+    CompVertices(other.CompVertices),
+    CompShader(other.CompShader),
+    CompVertexBufferID(other.CompVertexBufferID),
+    CompVertexArrayID(other.CompVertexArrayID),
+    CompScreenInputTex(other.CompScreenInputTex),
+    CompScreenOutputTex(other.CompScreenOutputTex),
+    CompScreenOutputFB(other.CompScreenOutputFB)
 {
+    other.CompScreenOutputFB = {};
+    other.CompScreenInputTex = {};
+    other.CompScreenOutputTex = {};
+    other.CompVertexArrayID = {};
+    other.CompVertexBufferID = {};
+    other.CompShader = {};
+}
+
+GLCompositor& GLCompositor::operator=(GLCompositor&& other) noexcept
+{
+    if (this != &other)
+    {
+        Scale = other.Scale;
+        ScreenH = other.ScreenH;
+        ScreenW = other.ScreenW;
+        CompScaleLoc = other.CompScaleLoc;
+        Comp3DXPosLoc = other.Comp3DXPosLoc;
+        CompVertices = other.CompVertices;
+
+        // Clean up these resources before overwriting them
+        OpenGL::DeleteShaderProgram(CompShader.data());
+        CompShader = other.CompShader;
+
+        glDeleteBuffers(1, &CompVertexBufferID);
+        CompVertexBufferID = other.CompVertexBufferID;
+
+        glDeleteVertexArrays(1, &CompVertexArrayID);
+        CompVertexArrayID = other.CompVertexArrayID;
+
+        glDeleteTextures(1, &CompScreenInputTex);
+        CompScreenInputTex = other.CompScreenInputTex;
+
+        glDeleteTextures(CompScreenOutputTex.size(), &CompScreenOutputTex[0]);
+        CompScreenOutputTex = other.CompScreenOutputTex;
+
+        glDeleteFramebuffers(CompScreenOutputFB.size(), &CompScreenOutputFB[0]);
+        CompScreenOutputFB = other.CompScreenOutputFB;
+
+        other.CompScreenOutputFB = {};
+        other.CompScreenInputTex = {};
+        other.CompScreenOutputTex = {};
+        other.CompVertexArrayID = {};
+        other.CompVertexBufferID = {};
+        other.CompShader = {};
+    }
+
+    return *this;
 }
 
 
-void GLCompositor::SetRenderSettings(const RenderSettings& settings) noexcept
+void GLCompositor::SetScaleFactor(int scale) noexcept
 {
-    int scale = settings.GL_ScaleFactor;
+    if (scale == Scale)
+        return;
 
     Scale = scale;
     ScreenW = 256 * scale;
@@ -170,13 +231,12 @@ void GLCompositor::SetRenderSettings(const RenderSettings& settings) noexcept
     glBindFramebuffer(GL_FRAMEBUFFER, 0);
 }
 
-void GLCompositor::Stop()
+void GLCompositor::Stop(const GPU& gpu) noexcept
 {
     for (int i = 0; i < 2; i++)
     {
-        int frontbuf = GPU.FrontBuffer;
         glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
-        glBindFramebuffer(GL_DRAW_FRAMEBUFFER, CompScreenOutputFB[frontbuf]);
+        glBindFramebuffer(GL_DRAW_FRAMEBUFFER, CompScreenOutputFB[gpu.FrontBuffer]);
 
         glClear(GL_COLOR_BUFFER_BIT);
     }
@@ -184,9 +244,9 @@ void GLCompositor::Stop()
     glBindFramebuffer(GL_FRAMEBUFFER, 0);
 }
 
-void GLCompositor::RenderFrame()
+void GLCompositor::RenderFrame(const GPU& gpu, GLRenderer& renderer) noexcept
 {
-    int frontbuf = GPU.FrontBuffer;
+    int frontbuf = gpu.FrontBuffer;
     glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
     glBindFramebuffer(GL_DRAW_FRAMEBUFFER, CompScreenOutputFB[frontbuf]);
 
@@ -204,21 +264,21 @@ void GLCompositor::RenderFrame()
     glUniform1ui(CompScaleLoc, Scale);
 
     // TODO: support setting this midframe, if ever needed
-    glUniform1i(Comp3DXPosLoc, ((int)GPU.GPU3D.GetRenderXPos() << 23) >> 23);
+    glUniform1i(Comp3DXPosLoc, ((int)gpu.GPU3D.GetRenderXPos() << 23) >> 23);
 
     glActiveTexture(GL_TEXTURE0);
     glBindTexture(GL_TEXTURE_2D, CompScreenInputTex);
 
-    if (GPU.Framebuffer[frontbuf][0] && GPU.Framebuffer[frontbuf][1])
+    if (gpu.Framebuffer[frontbuf][0] && gpu.Framebuffer[frontbuf][1])
     {
         glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 256*3 + 1, 192, GL_RGBA_INTEGER,
-                        GL_UNSIGNED_BYTE, GPU.Framebuffer[frontbuf][0]);
+                        GL_UNSIGNED_BYTE, gpu.Framebuffer[frontbuf][0].get());
         glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 192, 256*3 + 1, 192, GL_RGBA_INTEGER,
-                        GL_UNSIGNED_BYTE, GPU.Framebuffer[frontbuf][1]);
+                        GL_UNSIGNED_BYTE, gpu.Framebuffer[frontbuf][1].get());
     }
 
     glActiveTexture(GL_TEXTURE1);
-    reinterpret_cast<GLRenderer*>(GPU.GPU3D.GetCurrentRenderer())->SetupAccelFrame();
+    renderer.SetupAccelFrame();
 
     glBindBuffer(GL_ARRAY_BUFFER, CompVertexBufferID);
     glBindVertexArray(CompVertexArrayID);