extend to support rendering to RenderTarget/OpenGL texture on Linux

linux/filament_texture.cc

@@ -0,0 +1,74 @@
+#include <flutter_linux/flutter_linux.h>
+#include <flutter_linux/fl_texture_registrar.h>
+#include <flutter_linux/fl_texture.h>
+#include <flutter_linux/fl_texture_gl.h>
+#include <gtk/gtk.h>
+#include <sys/utsname.h>
+
+#include <epoxy/gl.h>
+#include "include/polyvox_filament/filament_texture.h"
+
+#include <iostream>
+#include <vector>
+
+
+G_DEFINE_TYPE(FilamentTextureGL,
+              filament_texture_gl,
+              fl_texture_gl_get_type())
+
+static gboolean
+filament_texture_populate (FlTextureGL *texture,
+                        uint32_t *target,
+                        uint32_t *name,
+                        uint32_t *width,
+                        uint32_t *height,
+                        GError **error) {
+  FilamentTextureGL *self = FILAMENT_TEXTURE_GL (texture);
+  *target = GL_TEXTURE_2D;
+  *name = self->texture_id;
+  *width = self->width;
+  *height = self->height;
+  return TRUE;
+}
+
+void filament_texture_gl_dispose(GObject* object) {
+    G_OBJECT_CLASS(filament_texture_gl_parent_class)->dispose(object);
+}
+
+void filament_texture_gl_class_init(FilamentTextureGLClass* klass) {
+  G_OBJECT_CLASS(klass)->dispose = filament_texture_gl_dispose;
+  FL_TEXTURE_GL_CLASS(klass)->populate = filament_texture_populate;
+}
+
+void filament_texture_gl_init(FilamentTextureGL* self) { }
+
+FLUTTER_PLUGIN_EXPORT FlTexture* create_filament_texture(uint32_t width, uint32_t height, FlTextureRegistrar* registrar) {   
+  auto textureGL = FILAMENT_TEXTURE_GL(g_object_new(filament_texture_gl_get_type(), nullptr));
+  textureGL->width = width;
+  textureGL->height = height;
+
+  g_autoptr(FlTexture) texture = FL_TEXTURE(textureGL);
+
+  
+  glGenTextures(1, &textureGL->texture_id);
+
+  glBindTexture(GL_TEXTURE_2D, textureGL->texture_id);
+
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+
+  glTexImage2D (GL_TEXTURE_2D, 0, GL_RGBA8, textureGL->width, textureGL->height, 0, GL_RGBA,
+                  GL_UNSIGNED_BYTE, 0);
+   
+    if(fl_texture_registrar_register_texture(registrar, texture) == TRUE) { 
+
+      if(fl_texture_registrar_mark_texture_frame_available(registrar,
+                                                      texture) != TRUE) {
+        std::cout << "FAILED" << std::endl;
+        return nullptr;
+      } 
+    }
+    return texture;
+}