nvdec_gl: load OpenGL function from GL

This removes the dependency from the vtable in vlc_gl_api_t.

modules/hw/nvdec/nvdec_gl.c

@@ -58,6 +58,12 @@ typedef struct {
     CUcontext cuConverterCtx;
     CUgraphicsResource cu_res[PICTURE_PLANE_MAX]; // Y, UV for NV12/P010
     CUarray mappedArray[PICTURE_PLANE_MAX];
+
+    struct {
+        PFNGLBINDTEXTUREPROC BindTexture;
+        PFNGLGETERRORPROC GetError;
+        PFNGLTEXIMAGE2DPROC TexImage2D;
+    } gl;
 } converter_sys_t;
 
 #define CALL_CUDA(func, ...) CudaCheckErr(VLC_OBJECT(interop->gl), devsys->cudaFunctions, devsys->cudaFunctions->func(__VA_ARGS__), #func)
@@ -76,11 +82,11 @@ static int tc_nvdec_gl_allocate_texture(const struct vlc_gl_interop *interop, GL
 
     for (unsigned i = 0; i < interop->tex_count; i++)
     {
-        interop->vt->BindTexture(interop->tex_target, textures[i]);
-        interop->vt->TexImage2D(interop->tex_target, 0, interop->texs[i].internal,
+        p_sys->gl.BindTexture(interop->tex_target, textures[i]);
+        p_sys->gl.TexImage2D(interop->tex_target, 0, interop->texs[i].internal,
                            tex_width[i], tex_height[i], 0, interop->texs[i].format,
                            interop->texs[i].type, NULL);
-        if (interop->vt->GetError() != GL_NO_ERROR)
+        if (p_sys->gl.GetError() != GL_NO_ERROR)
         {
             msg_Err(interop->gl, "could not alloc PBO buffers");
             return VLC_EGENERIC;
@@ -92,7 +98,7 @@ static int tc_nvdec_gl_allocate_texture(const struct vlc_gl_interop *interop, GL
         result = CALL_CUDA(cuGraphicsSubResourceGetMappedArray, &p_sys->mappedArray[i], p_sys->cu_res[i], 0, 0);
         result = CALL_CUDA(cuGraphicsUnmapResources, 1, &p_sys->cu_res[i], 0);
 
-        interop->vt->BindTexture(interop->tex_target, 0);
+        p_sys->gl.BindTexture(interop->tex_target, 0);
     }
 
     CALL_CUDA(cuCtxPopCurrent, NULL);
@@ -167,6 +173,19 @@ static int Open(vlc_object_t *obj)
         vlc_decoder_device_Release(device);
         return VLC_ENOMEM;
     }
+
+    p_sys->gl.BindTexture =
+        vlc_gl_GetProcAddress(interop->gl, "glBindTexture");
+    assert(p_sys->gl.BindTexture);
+
+    p_sys->gl.GetError =
+        vlc_gl_GetProcAddress(interop->gl, "glGetError");
+    assert(p_sys->gl.GetError);
+
+    p_sys->gl.TexImage2D =
+        vlc_gl_GetProcAddress(interop->gl, "glTexImage2D");
+    assert(p_sys->gl.TexImage2D);
+
     for (size_t i=0; i < ARRAY_SIZE(p_sys->cu_res); i++)
         p_sys->cu_res[i] = NULL;
     p_sys->cuConverterCtx = NULL;