Add SpirvHelper (Shader cross compilation)

- Make OpenGL2 and OpenGL3 use the same base shaders (using SpirvHelper)
- Add Transpose func to Mat4

backends/include/pd_system/gfx_opengl2.hpp

@@ -39,7 +39,5 @@ class GfxOpenGL2 : public GfxDriverBase<GfxOpenGL2Config> {
   int pLocTex = 0;
   int pLocAlfa = 0;
   int pLocProjection = 0;
-  static const char* pVertCode;
-  static const char* pFragCode;
 };
 }  // namespace PD

backends/include/pd_system/gfx_opengl3.hpp

@@ -39,7 +39,5 @@ class GfxOpenGL3 : public GfxDriverBase<GfxOpenGL3Config> {
   int pLocTex = 0;
   int pLocAlfa = 0;
   int pLocProjection = 0;
-  static const char* pVertCode;
-  static const char* pFragCode;
 };
 }  // namespace PD

backends/include/pd_system/shaders.hpp

@@ -0,0 +1,51 @@
+#pragma once
+
+namespace PD {
+namespace Shaders {
+inline static const char* VertCode = R"(
+  #version 460
+  
+  layout(location = 0) in vec2 pos;
+  layout(location = 1) in vec2 uv;
+  layout(location = 2) in vec4 color;
+  
+  layout(location = 0) out vec2 oUV;
+  layout(location = 1) out vec4 oColor;
+  
+  // Probably forgot about this matrix and
+  // searched hours for why the rendering isn't working :/
+  layout(set = 0, binding = 0) uniform UBO {
+    mat4 projection;
+  } ubo;
+  
+  void main() {
+      gl_Position = ubo.projection*vec4(pos, 0.0, 1.0);
+      oUV = uv;
+      oColor = color;
+  }
+  )";
+
+inline static const char* FragCode = R"(
+  #version 460
+      
+  layout(location = 0) in vec2 oUV;
+  layout(location = 1) in vec4 oColor;
+  
+  uniform sampler2D tex;
+  layout(push_constant) uniform PushData {
+    int alfa;
+  } push;
+
+  out vec4 FragColor;
+      
+  void main() {
+    vec4 tc = texture(tex, oUV);
+    if (push.alfa != 0) {
+      FragColor = vec4(oColor.rgb, tc.a * oColor.a);
+    } else {
+      FragColor = tc * oColor;
+    }
+  }
+  )";
+}  // namespace Shaders
+}  // namespace PD

backends/include/pd_system/spirv-helper.hpp

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <glslang/Public/ResourceLimits.h>
+#include <glslang/Public/ShaderLang.h>
+
+#include <pd/common.hpp>
+
+namespace PD {
+class SpirvHelper {
+ public:
+  enum class Format {
+    GLSL,
+    HLSL,
+    MSL,  // Not supported yet
+    SPIRV,
+  };
+
+  enum class Stage {
+    Vertex = 0,
+    Geometry = 3,
+    Fragment = 4,
+  };
+
+  SpirvHelper() = default;
+  ~SpirvHelper() = default;
+
+  static void Init();
+  static void Finalize();
+  static void SetupResources(TBuiltInResource& resources);
+  static std::vector<PD::u32> GLSL2SPV(Stage stage, const char* code,
+                                       bool vulkan_mode = false);
+  static std::string SPV2GLSL(const std::vector<PD::u32>& spirv, int version,
+                              bool es = false);
+  static std::string SPV2HLSL(const std::vector<PD::u32>& spirv, int version);
+};
+}  // namespace PD