Shadergen: Minimize shader compilation time by caching the default VS

include/PICA/shader_gen.hpp

@@ -35,7 +35,7 @@ namespace PICA::ShaderGen {
 	  public:
 		FragmentGenerator(API api, Language language) : api(api), language(language) {}
 		std::string generate(const PICARegs& regs, const PICA::FragmentConfig& config);
-		std::string getVertexShader(const PICARegs& regs);
+		std::string getDefaultVertexShader();
 
 		void setTarget(API api, Language language) {
 			this->api = api;

include/renderer_gl/renderer_gl.hpp

@@ -66,6 +66,9 @@ class RendererGL final : public Renderer {
 	OpenGL::Texture lightLUTTexture;
 	OpenGL::Framebuffer screenFramebuffer;
 	OpenGL::Texture blankTexture;
+	// The "default" vertex shader to use when using specialized shaders but not PICA vertex shader -> GLSL recompilation
+	// We can compile this once and then link it with all other generated fragment shaders
+	OpenGL::Shader defaultShadergenVs;
 
 	// Cached recompiled fragment shader
 	struct CachedProgram {

src/core/PICA/shader_gen_glsl.cpp

@@ -34,7 +34,7 @@ static constexpr const char* uniformDefinition = R"(
 // This is particularly intuitive in several places, such as checking if a LUT is enabled
 static constexpr int spotlightLutIndex = 2;
 
-std::string FragmentGenerator::getVertexShader(const PICARegs& regs) {
+std::string FragmentGenerator::getDefaultVertexShader() {
 	std::string ret = "";
 
 	switch (api) {

src/core/renderer_gl/renderer_gl.cpp

@@ -162,6 +162,10 @@ void RendererGL::initGraphicsContextInternal() {
 	OpenGL::setViewport(oldViewport[0], oldViewport[1], oldViewport[2], oldViewport[3]);
 
 	reset();
+
+	// Initialize the default vertex shader used with shadergen
+	std::string defaultShadergenVSSource = fragShaderGen.getDefaultVertexShader();
+	defaultShadergenVs.create({defaultShadergenVSSource.c_str(), defaultShadergenVSSource.size()}, OpenGL::Vertex);
 }
 
 // The OpenGL renderer doesn't need to do anything with the GL context (For Qt frontend) or the SDL window (For SDL frontend)
@@ -810,12 +814,10 @@ OpenGL::Program& RendererGL::getSpecializedShader() {
 	OpenGL::Program& program = programEntry.program;
 
 	if (!program.exists()) {
-		std::string vs = fragShaderGen.getVertexShader(regs);
 		std::string fs = fragShaderGen.generate(regs, fsConfig);
 
-		OpenGL::Shader vertShader({vs.c_str(), vs.size()}, OpenGL::Vertex);
 		OpenGL::Shader fragShader({fs.c_str(), fs.size()}, OpenGL::Fragment);
-		program.create({vertShader, fragShader});
+		program.create({defaultShadergenVs, fragShader});
 		gl.useProgram(program);
 
 		// Init sampler objects. Texture 0 goes in texture unit 0, texture 1 in TU 1, texture 2 in TU 2, and the light maps go in TU 3

third_party/opengl/opengl.hpp

@@ -373,7 +373,7 @@ namespace OpenGL {
 		// Returns whether compilation failed or not
 		bool create(const std::string_view source, GLenum type) {
 			m_handle = glCreateShader(type);
-            const GLchar* const sources[1] = { source.data() };
+			const GLchar* const sources[1] = {source.data()};
 
 			glShaderSource(m_handle, 1, sources, nullptr);
 			glCompileShader(m_handle);
@@ -394,6 +394,17 @@ namespace OpenGL {
 
 		GLuint handle() const { return m_handle; }
 		bool exists() const { return m_handle != 0; }
+
+		void free() {
+			if (exists()) {
+				glDeleteShader(m_handle);
+				m_handle = 0;
+			}
+		}
+
+#ifdef OPENGL_DESTRUCTORS
+		~Shader() { free(); }
+#endif
 	};
 
     struct Program {
@@ -431,6 +442,10 @@ namespace OpenGL {
 				m_handle = 0;
 			}
 		}
+
+#ifdef OPENGL_DESTRUCTORS
+		~Program() { free(); }
+#endif
 	};
 
     static void dispatchCompute(GLuint groupsX = 1, GLuint groupsY = 1, GLuint groupsZ = 1) {